2 Jour. Chem. Soc., Mar. 1886.

3 Jour. Soc. Chem. Ind., 1894. p.218.

4 Died, April 1905.

5 There is a copy in the British Museum and also in the Patent Office Library.

6 Some further analyses of grains at Trent Bridge gave the following results:—

M.C. Lamb has found in sheep grains split for skivers the following amounts:—

The figures are all percentages calculated on the dry weight of the skin.

Munro Payne (Tanners’ Year Book, 1905, p.75) gives the following amounts of lime as Ca(OH)₂ in limed hides, calculated on dry weight at 212°F.:—

7 From the molecular weights it will be seen that 74grm. of calcium hydrate, equivalent to 56grm. of lime (CaO), require 73grm. of HCl gas for neutralization. This quantity of gas is contained in 265grm. of commercial hydrochloric acid of 18° BÉ., or about 230 c.c.—that is, for 100grm. CaO, 410c.c. of 18° BÉ. acid are required; hence for the 100 kilos wet grain containing 400grm. CaO, 1640c.c. of acid are required for complete neutralization. It is impracticable to use this amount of acid, for the reasons stated above.

8 Tanners’ Year Book, 1911, p.59.

9 See Chapter III.

10 See also L’Acide Butyrique dans la Tannerie, Urbain J. Thuau, Le Cuir, Aug. 1910. Also Collegium, 1910, pp.347, 363.

11 Le dÉchaulage des Peaux en tripe, Ettore Guisiana (Turin), Coll. 1910, p.14.

12 Verfahren zum Beizen von HaÜten, Ledertechnische Rundschau, No. 24, 1910. Coll. 1910, p.372.

13 When the puer is dirty it should be diluted with water and strained through a bag, or the diluted puer may be put into a tub and the heavy grit and dirt allowed to fall to the bottom of the vessel. Puer from hunting kennels is usually clean enough to use without this process.

14 The quantities of puer used vary considerably in different works. At Trent Bridge, 10 to 15lb. of wet puer from hunting kennels are used per 100lb. of wet pelt. In a German works, 15 kilos of fairly dry dog dung are used per 100 kilos of pelt (BlÖsse). In an American works, two buckets (one bushel) wet dog dung were used to puer 10 dozens of 8lb. calf skins. This is equal to about 62lb. of puer to 100lb. of skin, which seems an excessive quantity. In an Italian works, two kilos dry dung were used to 20 skins of sheep, equivalent to about four kilos per 100. In an English tannery, 100 hides for harness leather required four bushels by measure of pigeon dung, costing 1s. 6d. per bushel (one bushel equals eight gallons).

15 A German firm, who supply dry dog and pigeon dung for bating purposes, recommend that the material should be spread in a warm room at 30°C., and moistened up to 80 per cent. of its weight with an infusion of oat straw, and continuously turned over until completely softened. Other materials may be used for the fermenting fluid in place of the oat straw infusion, such as broth made from waste fleshings, whey, or even a simple inorganic solution, such as is used for cultivating bacteria, consisting of—

2 parts potassium phosphate.
1 part magnesium sulphate.
1 part calcium nitrate.
1·5 part calcium chloride.
100 parts water.

This procedure is neither more nor less than an application of the principles of bacterial cultivation and propagation, shown to be practically useful in the bating process by Professor H. Becker, of Frankfort, and by the Author in various publications (see Chapter VII.).

16 There is considerable variation in the length of time required to bring down the skins. Lamb states that half an hour is frequently sufficient, but at Trent Bridge 2–3 hours are generally required. The causes of the variation are not altogether clear, but depend partly on the previous history of the goods (fellmongering, liming, etc.), and partly on the water used.

17 The original Turney scudding machine, was invented in 1871, and patented in that year. The specifications are numbered 1351, and 3310, 1871. It was also patented in America. Specification No. 131,480, dated September 17, 1872. Improvements in apparatus for cleaning and scouring hides and skins.

18 Limed sheep grains, or Pelts, which have been limed for splitting, contain from 3 per cent. to 6 per cent. CaO on the dry skin (see footnote, p.7), and about 80 per cent. of water. In a typical case of a fully limed grain, the lime was found to be distributed as follows:—

Thus, 75 per cent. of the total lime in the skin was in the caustic state. If the skin be cut during the progress of the bating operation, and a solution of phenolphthalein applied to the cut surface, the course of bating may be followed, and it will be found that the caustic lime disappears from the skin in a very short period of time, accompanied by the sudden collapse of the fibres. We shall treat of this more fully in Chapter III. After puering, the lime (CaO) contained in the skin, amounts to 0·5 to 0·9 per cent., calculated on the dry skin. This lime is in a perfectly neutral state, and is more or less in combination with the fibre of the skin. The exact state in which the lime exists in the skin after puering is not known, and would form a very interesting subject for research.

19 Schmidt, and Strassburger, Die FÆces des Menchen (Hirschwald, Berlin), 1901.

20 Lambling, PrÉcis de Biochimie, 1911, p.221.

21 Another sample contained 136grm. dry matter.

22 Gaultier. See also analysis given in Chapter VI.

23 Abderhalden, Physiological Chemistry.

24 Cf. Mann. Chemistry of the Proteids, 1906, p.432.

25 The cholesterol was obtained by extracting the dry puer with ether, saponifying with alcoholic potash. Shaking out the unsaponifiables with ether, evaporating to dryness. The residue was taken up with absolute alcohol, decolorized with animal charcoal. On cooling, characteristic crystals of cholesterol separated. Hoppe-Seyler finds from 1 per cent. to 4 per cent. cholesterol in fÆces. See also Gaultier, Coprologie Clinique, p. 160.

26 For qualitative tests for the colouring matters, see Gaultier, PrÉcis de Coprologie Clinique, p.159.

27 English Patent, 21202, 1909. See also Chapter VIII.

28 Probably syntonin, or bodies of a similar nature (see Allen. Comm. Org. Anal. iv. p.4). The supposition is supported by the fact that solutions of puer have a slight laevorotatory action on polarized light.

See also note on Van Liers paper, Coll. 376, 1909, p.823.

29 See paper entitled, “The Employment of the Electrometric Method for the Estimation of the Acidity of Tan Liquors,” by H.J.S. Sand, Ph.D. D.Sc., and D.J. Law, B.Sc. F.I.C., J.S.C.I. 1911, p.3; also Part II., by Wood, Sand and Law, J.S.C.I. 1911, p.872.

30 Eitner, Der Gerber, 566, p.77, states that little or no neutralization of lime by acids or acid salts takes place in the bate.

31 Ber. Deutsch. Botan. Ges. 1900, xviii. 32, J.S.C.I. 1900, 386.

32 Centr. Bakt. Parasitenk, ii. Abt. viii., 393, etc., J.S.C.I. 1902, 1151.

33 Fitz (Berichte, 1876–1884, see Herfeldt, J.S.C.I. May 31, 1895), has shown that lactates in dung are decomposed by bacteria, the chief product being propionic acid.

34 Rettger, Amer. Jour. of Physiol., viii. p.284; Koch’s Jahresbericht, 1903, p.112.

35 Deliming with acids when carefully done takes out more lime than the puer, without in any way injuring the skin, but when tanned with sumac the bellies and axilla are harsh, and of a browner colour than in a puered skin. Analysis showed no more lime in the brown portions than in the centre of the skin, where the colour was quite bright and satisfactory.

36 Vide Procter, L.I.L.B., 1908, p.64.

37 In a blank experiment to determine this, 0·0476grm. N per litre was found to be brought into solution from the puer.

38 Stiasny, On Old Limes. Collegium 1910, p.181.

39 Stiasny. Collegium 1910, p.184.

40 Ueber die Zusammensetzung des beim Beizen von Lammfellen mit Hundekot abfÄllenden “festen Schmutzes”: ein Beitrag zur Beizenfrage.—Coll., 1911, p.445.

41 Urea is present to the extent of 5 per cent. in samples of Peruvian guano.

42 Manures, Natural and Artificial, W. Ivison Macadam. Jour. Soc. Chem. Ind. 1888, p.79.

43 Principles of Leather Manufacture, p.179.

44 Stiasny, Kritische und Experimentelle BeitrÄge zur AufklÄrung der GerbvorgÄnge. Collegium 1908, p.117.

Wood, Compounds of Gelatin and Tannin. Collegium 1908, p.494.

45 Allen, Comm. Org. Analysis, iv. p.459.

46 Procter, Colloidal Chemistry. Brit. Assoc. Rep. 1908.

47 M. Planck, Zeit. f. Phys. Chem. xlii. p.584 (1903).

48 Sull’ appliccazione della bilancia idrostatica per il controllo della concia delle pelli, Milan, 1903.

49 See Kohlrausch, An Introduction to Physical Measurements, 1894, p.43. See also, Weighing Hides in Water, C.E. Parker and G.H. Russell, Tanners’ Year-Book 1905, p.45.

50 Wiedemann’s Annal d. Physik, xxxv. p.352 (1888).

51 Th. KÖrner, 10 Jahres. Bericht, d. Deutsch. Gerberschule zu Freiberg, 1899, p.32.

52 Procter, Ueber die Einwirkung VerdÜnnter Sauren und SalzlÖsungen auf Gelatine, Kolloid Chem. Beihefte, 1911, ii. p.243.

53 Duvernoy, E. Wiedemann, and LÜdeking, Wied. Ann. xxv. 1885, p. 145.

54 Rodewald. Thermodynamik der Quellung, Zeit. f. Phys. Chem. xxiv. 1897, p.193.

55 Zur Lehre von d. Quellung, Wied. Ann. liii. 1894, p.564.

56 Nernst and SchÖnfliess. Einleitung in die mathematische Behandlung der Naturwissenschaft, MÜnchen 2 Aufl. 67.

57 See also Colloidal Chemistry, H.R. Procter, M.Sc., Brit. Assoc. Reports, Dublin, 1908.

58 Wilhemy. Pogg. Ann. cxix. pp.121, 122.

59 Colloidal Chemistry, p.19.

60 Allgemeine Chem. d. Kolloide, p.13.

61 Pribram, Die Bedeutung der Quellung und Entquellung fÜr physiologische und pathologische Erscheinungen. Kolloid Chem. Beihefte, ii. p.1.

62 Perrin, Kolloid Chem. Beihefte, i. p.221.

63 A particle of gamboge in a colloidal solution has a mass 10⁹ times that of a molecule of hydrogen.

64 Acids in Tan Liquors, Journ. Soc. of Chem. Ind., 1910, p.1354.

65 Journ. Soc. Chem. Ind., 1911, p.3.

66 Ibid., 1911, p.872.

67 An improved form of hydrogen electrode devised by Dr. H. Sand may now be obtained from UniversitÄts-mecanikes Fritz KÖhler, Leipzig. It is shown at I in Fig.10.

68 It is necessary to use pure hydrogen. This may now be obtained commercially from the Knowles’ Oxygen Co., Wolverhampton.

69 The formula for calculating p+H for the N/1 auxiliary electrode used is as follows:—

Since p = (0·283 + 0·0575 log 1/C volt)

log 1/C = p+H = p – 0·283/0·0575

p = potential difference found

C = concentration of hydrogen-ions.

70 Vide Soerensen, Sur la mesure et l’importance de la concentration des ions hydrogÈne dans les rÉactions enzymatiques. Comp. rend. Lab. de Carlsberg, 8me. vol. 1^ere livraison, Copenhagen, 1909.

71 Minot, Address to Amer. Assoc. for Advancement of Science, Minneapolis, Dec. 29, 1910. Nature, 1911, p.96.

72 The apparatus was constructed by Mr. W. Linney, of the University College, Nottingham.

Since this apparatus was constructed Professor H.R. Procter has informed me that an appliance devised by Mr. Anderson, of the Leeds University, for measuring the thickness of leather under varying pressures, has been in use in the leather industries department for some months for the purpose of measuring the proportion of the permanent to elastic compression.

73 A good microscope, with 1/12 oil-immersion objective and Abbe condenser, is necessary for bacteriological work. The new dark-ground condenser made by James Swift and Son, London, is extremely useful for examining living bacteria under high magnifications.

74 The most recent method is to preserve the slides without cover-glasses: a drop of cedar oil is placed directly on the preparation, and, after examination, carefully washed off with xylol. Care should be taken not to touch the preparation with the fingers.

75 Masson et Cie, Publishers.

76 Klein, E., Micro-organisms and Disease (Macmillan), p.22. See also, Kanthack and Drysdale, Practical Bacteriology (Macmillan 1896), p.86.

77 The subject is not so far removed from direct human interest as one might suppose. For many years Metchnikoff, in Paris, has been studying the bacterial flora of the human intestines. His theory is, that old age is caused by the poisonous products of these intestinal bacteria, and he proposes to counteract the effects of these poisonous organisms, by introducing into the system large quantities of lactic acid bacteria, either in the form of tabloids, or in the form of sour milk cultures.

78 For the demonstration of flagellÆ, the material is taken from a culture on solid media—a young agar culture is best. Make a dilution by Soyka’s method (p.103), dry and fix on a cover-glass as described, p.88, then proceed as follows:—

1. Mordant with a mixture of 10c.c. 20 per cent. tannin solution, 5c.c. cold saturated ferrous sulphate, 1c.c. fuchsin or wool-black solution. This solution is put on the preparation, which is then heated for one minute until steam is given off.

2. Wash under the tap, then in alcohol.

3. Stain with anilin-water-fuchsin solution, prepared by dissolving the dye in anilin-water and adding 1 per cent. of a 1 per cent. solution of caustic soda until the liquid begins to go cloudy.

4. Wash off the stain with distilled water.

79 “Beitrag zur Bakterienflora des Darmes,” Archiv f. Hygiene, Bd. 26, p.293.

80 Zeit. f. Offt. Chem., Heft. xxiii. Jahr. X. p.447.

81 Dr. A.C. Houston has been kind enough to make an examination of B. erodiens, and to ascertain its action on various sugars. It produces fluorescence in neutral-red broth cultures, acid and gas in lactose cultures, indol, and acid, and clot in milk cultures. It ferments dulcite with production of acid, but not cane sugar, adonite, inulin, inosite, salicin, or raffinose.

82 The modification of Soyka’s method of making attenuations of bacteria is that of GÜnther (Bakteriologie, 1898, p.204), and is carried out as follows:—On the inner surface of the cover of a sterile Petri dish (which is to be used for making the plate culture), place four drops of sterile broth, or sterile water; inoculate the first drop, by means of a platinum needle, with the material to be examined; heat the needle in the flame, dip it into the first drop, and, with the liquid adhering, inoculate the second drop. Proceed in this way, each time heating the needle, to the fourth drop. From this fourth drop a tube of nutrient gelatin is inoculated, and poured on to the plate. The cover is then put on, and the plate put into the incubator. The drops on the cover do not in any way contaminate the culture.

83 Villon found that Bacterium pilline developed 0·142 per cent. ammonia in ten days in lime liquors used for unhairing skin.

84 Cultures made from old limes have, however, not been found effective in bating.

85 Journ. f. Prakt. Chem., Bd. xvii., 1878; see also Stoklasa, Cent. Bl. f. Bakt. vi., p.526.

86 Proc. Roy. Soc., lxvii., 1900.

87 Reynolds Green, Fermentation, p.350.

88 SensibilitÉ de la peau verte, et de la peau aprÈs l’Échauffe, les pelains, et les confits, À l’Égard de la chaux du sel, et de l’acide acÉtique. Georges Abt et Edmund Stiasny, Collegium 1910, p.1 9.

89 See Les Anaerobies, Jungano and Distaso (Masson et Cie Paris, 1910).

90 The Bacteriology of the Leather Industry, J.S.C.I., 1910, p.666.

91 Reprinted from the Journal of the Society of Chemical Industry, February 15, 1906, No. 3, vol.xxv. The numbers in brackets refer to the Bibliography, Chapter XI.

92 J.S.C.I., 1894, 218.

93 J.S.C.I., 1893, 442.

94 “The Nature of Enzyme Action,” by Dr. W.M. Bayliss, FRS.

95 The important discoveries of MM. Paul Sabatier and Senderens on the catalytic action of finely divided metals, notably nickel and copper, have recently been extended to a study of the catalytic action of various metallic oxides. In the Comptes rendus, MM. Paul Sabatier and A. Mailhe give an account of a new synthetic method, based on the catalytic effect of titanium oxide, which would appear to possess many practical applications. They show that if a column of titanium dioxide is maintained at a temperature of 280°–300°C., and a mixture of the vapours of a primary alcohol and a fatty acid (other than formic acid) is led over it, the corresponding ester is formed. The same limit is here reached instantaneously as was found by Berthelot after prolonged contact. An excess of either constituent favours the limit of combination of the other. Following this method, the methyl, ethyl, propyl, butyl, isobutyl, and isoamyl esters of acetic, propionic, butyric, isobutyric, isovaleric and caproic acids have been prepared. Esters of benzyl alcohol have also been readily obtained by this method. The inverse action—the direct hydrolysis of esters by water—is also easily effected, and the use of titanium dioxide reduces any secondary reactions to a negligible amount. See Nature, March 9, 1911, p.54. See also Dr. Sand’s paper—bibliography.

96 There are apparent exceptions and complications of this law which we shall not here enter into, except to say that they may be explained by the fact that the action of some enzymes is reversible (see p.141, under lipase.)

97 “Zeit. f. Hygiene,” Bd. xlix. p.135.

98 Les Enzymes, Dr. Jean Effront, Paris, 1899.

99 Zeit. f. Physiol. Chem. xli. f. 153 (1904). See also the articles by Mr. A. Seymour Jones, B.Sc., writing under the pseudonym of “Heof Joppa,” in the Leather Trades’ Review, July 19, 1911, p.540; and Aug. 16, 1911, p.625.

100 See, however, the recent paper by Eberle and Krall, Ueber den Nachweis des Trypsins im Hundekot, Collegium 1911, p.201, in which the authors endeavour to show the presence of unchanged trypsin in dog dung. Their proof depends upon the action of an antipancreatic serum on infusions of dog dung based on the work of Achalme, Ann. de l’Inst. Pasteur, 1901, p.737. See also the criticism on this paper by Dr. Otto RÖhm and Dr. Max Goldman, Collegium, 1911, p.265. Hammarsten (Physiol. Chemistry, 1911, p.494) states that “among the secretions which undergo putrefaction in the intestine, the pancreatic juice, which putrefies most readily, takes place first.”

101 Duclaux. See Bibliography.

102 Koch’s Jahresbericht Über GÄrhungs Organismen, 1908, 635.

103 J.S.C.I., vol.xiii., 1894, p.218.

104 The word pancreatin is used throughout in the sense of pancreas extract. As is well known, this contains several enzymes, trypsin, steapsin, maltase, and also a rennin.

105 Also known as steapsin, or pyolin (Allen, p.357, vol.iv., Comm. Org. Analysis).

106 In the digestion of fat by dogs the glycerol produced is all absorbed before the ileum is reached, so that none exists in the excrement. (Levites, Chem. Soc. Abst. 1907, vol.iv. p.891.)

107 Another instance of the reversibility of enzyme action is the secretion of a peptolytic enzyme, by B. pyocyaneus; i.e. it has the power of synthesizing proteins, as well as of decomposing them. (Zak. Chem. Soc. Abst. 1907, p.996.)

108 Chem. Soc. Annual Reports IV., 1907, p.252.

109 Hammarsten, p.70.

110 Gulland, Ency. Britt. iv., p.83.

111 Appelius, Technische Briefe, No. 23, April 1909.

112 Harden, see Bibliography.

113 References to bating:

Procter. Text-book of Tanning, 1885, 184.
Der Gerber, x. (1884), 197, Mistbeizen.
Der Gerber, xv. (1889), 267.
J. Anal, and Appl. Chem., 1893, vii. 87, 95.
J.S.C.I., xii. 530, Palmer and Sandford.
Salomon, W.J., Tech. Quarter, 1892, v. 81, etc.
J.S.C.I., xii. 774, ix. 27.

114 Harris and Gow, Jour. of Physiol., xiii. 469. G. Tammian, Zeitschr. f. Physiol. Chem., xv. 271. O. Loew., J. Prak. Chem., 37, 101. J.S.C.I., 1888, 224.

115 This is not invariably the case: other samples of puer examined have given off NH₃ when similarly treated, but only in small quantity. A similar instance has been observed by Rideal and Orchard in the liquefaction and decomposition of gelatin by B. fluorescens liquefaciens (The Analyst, October 1897), where the quantity of ammonia produced was insignificant, amounting even after 16 days’ incubation to only 0·168grm. of N per 100c.c., corresponding to 0·204grm. of ammonia.

116 Procter, Text Book of Tanning, p.85.

117 According to the text books; but for later researches see Paal and Schilling, Chem. Zeit. 1895, 1487; also J.S.C.I., 1898, 589.

118 H.K. Procter, “Text Book of Tanning,” 1885, p.18.

119 See Procter, “Text Book of Tanning,” pp.8 and 21.

120 Since the above was written, Severin (Centr.-Bl. iii. [2], 628) has described seven other species of bacteria, isolated from horse dung; for the description and property of these the original memoir must be consulted. Popp and Becker, German Patent 86,335, 28, describe fourteen species which they isolated from dog and pigeon dung, of which three have considerable bating action on skins, and which form the subject of the patent. Some of these are probably identical with organisms in the above list.

121 Centr.-Bl. ii. [1], 97.

122 J.S.C.I., 1894, March 31, 218–221.

123 See Gamgee, Phys. Chem. 2.

124 Ann. de Micrograph, ii. [6], March 20, 1896.

125 I did not consider it necessary to purify the enzymes, the object being to examine the action of the bacterial products apart from the living organisms.

126 Reprinted from the Journal of the Society of Chemical Industry, November 30, 1899, No. 11, vol.xviii.

127 10 Jahresber. d. Deutsch. Gerberschule zu Freiberg, 1898–99: BeitrÄge zur Kentniss der wissenschaftlichen Grundlagen der Gerberei, p.32.

128 J.S.C.I., 1898, p.1011, see previous paper, p.152.

129 Ber. 25, 1202; also Allen, “Comm. Org. Analysis,” iv., 466. F. Marpmann, Centralblatt f. Bakt. 2, 5, 67.

130 Rev. Gen. des Sciences, 1899, p.380.

131 Jorgensen, the “Micro-organisms of Fermentation,” p.20.

132 J.S.C.I., 1898, p.1012.

133 Leather Industries, Sept. 1898.

134 Principles of Leather Manufacture, p.160.

135 Text Book of Tanning, 1885, p.185.

136 The Manufacture of Leather, Philadelphia, 1885.

137 At the third Conference of the I.A.L.T.C., held in Copenhagen Aug., 1899, F. Kathreiner (Worms) brought forward communications from Wood (Nottingham) and Dr. Becker (Frankfort-on-Main) on artificial bates, from which it is shown by experiments and trials on a large scale at the works of Messrs. Doerr and Reinhart that both these gentlemen had worked out similar processes quite independently. Wiss. Techn. Beilage des Ledermarkt, 1899–1900, p.8. Bemerkungen Über die Wirkung der Kothbeizen, J.T. Wood. Idem, p.43.

Popp and Becker’s und Wood’s Ersatzmittel fÜr KÖthbeizen. Franz Kathreiner. Idem, p.50.

Einiges Über die Anwendung von Erodin einem Ersatzmittel fÜr Hundekoth u. dergl. in der Leder industrie. Bericht von Dr. H. Becker, Frankfort-on-Main. Wiss. Techn. Beilage des Ledermarkt. Bd. i., p.39.

Further particulars about the bate and its construction will be found in Chapter VIII.

138 One litre of erodin stock liquor (1 part erodin, 40 parts water) were used per kilo drained washed pelt, in the drum for 1 1/2 hours. In some cases less than 1 litre sufficed.

139 J.S.C.I., 1899, p.910. See also p.73.

140 J.S.C.I., 1898, p.1013.

141 See Chapter VIII.

142 See Chapter VIII.; also J.S.C.I. 1906, p.647.

143 A most useful source of information is Section XV. (Journal and Patent Literature) in the Journal of the Society of Chemical Industry, published fortnightly at Palace Chambers, Westminster. Abstracts of all patents relating to bates will be found under the above heading.

144 J.S.C.I. 1906, p.103.

145 J.S.C.I. 1898, pp.1010 to 1013, and 1899, pp.990 to 993.

146 An abstract of Wood’s work. 1901, p.148, section 4, p.149.

147 1. See German Patent No. 200,519 or British Patent No. 5377⁰⁸ Roehm, Esslingen.

148 1. See German Patent of Addition No. 203,889 Roehm, Esslingen.

149 2. See Abderhalden, “Text-book of Physiological Chemistry,” 1906, page555 and following.

150 1. See Abderhalden, “Text-book of Physiological Chemistry,” 1906, page556.

151 Bran examined by Kjeldahl’s process contained 2·2 per cent. N, equivalent to about 13–14 per cent. proteids.

152 Principles, pp.166–170.

153 Der Gerber, 1898, p.204.

154 Claflin (92) gives the limits of acidity for lactic bacteria from 0·02 to 0·5 per cent. Reynolds Green (97, p.346) gives the upper limit for B. acidi lactici as 8 per cent. lactic acid.

155 Der Gerber, 24, 570.

156 Jour. Soc. Chem. Ind., 1893, p.426.

157 Der Gerber, 1895, p.193, etc.

158 J.S.C.I., 1897, p.513.

159 Ibid., 1890, p.28.

160 Ibid., 1893, p.422.

161 J.S.C.I., 1890, 27.

162 Zeits. fÜr Biologie, xxiv. 105.

163 Jour. Chem. Soc., 1892, Trans. 254.

164 Der Gerber, xvi. (368), 4.

165 Method recommended to us by Dr. Frankland. Vide Jour. Chem. Soc. Trans. 59, p.94. Appendix II. Determ. of Vol. Acids by dist. with HCl.

166 Julius Wladika. Vide Der Gerber, xvi. 28. Zur Kenntniss der Organ. SÄuren in FichtenbrÜhen.

167 J.S.C.I. 1890, 27.

168 7grm. of yeast boiled in 100c.c. H₂O.

169 Prepared by precipitation with alcohol.

170 Prepared by heating starch and water to 50°C. for 18 hours and filtering.

171 Watts’ Dict., Old Ed. Cerealin discovered by MÈje MouriÉs, Comptes rend. 37, 351; 38, 505; 43, 1122; 48, 431; 50, 467.

172 Vide der Gerber xiv. 257 SÜsse Kleienbeize.

173 J.S.C.I. 1893, 422.

174 Potassium phosphate, 1grm.; magnesium sulphate, 0·2grm.; calcium chloride, 0·1; water, 1000 c.c. Vide Frankland and Frew, Trans. 1892, 255.

175 J.S.C.I. 1890, 28.

176 J.S.C.I. 1892, 422.

177 Vide Note on the Estimation of Butyric Acid, W.H. Willcox, J. Chem. Soc., Nov. 21, 1895.

178 Vide J. Chem. Soc. (Trans.), lix., 94, App. II.

179 J.S.C.I. 1893, 424; vide supra, p.254.

180 2000c.c. gave only about the same amount of acids as 1000c.c. fermentations. For percentages of acids, see table, p.281.

181 J.S.C.I. 1893, 423.

182 Schutzenberger, “Fermentation,” 1876, p.227.

183 Woodhead, “Bacteria and their Products,” p.125.

184 Die Stickstoffkonservirung im StalldÜnger, Jour. f. Landwirthsh., xlii. p.69.

185 J.S.C.I. 1910, p.331.

186 Celestial Objects, Webb, 1881.