Its chief disadvantage is that it works rather slowly, as the powder must be put into the die by hand with a small tool furnished with the machine. An automatically feeding machine of reasonable price is the "Eureka" Hand Tablet Machine, furnished by the F. J. Stokes Co., of Philadelphia (Fig. 2). This machine may also be obtained for motor power.

Detailed directions for the putting up and the use of these machines seem unnecessary here as they accompany the machine when sent out by the manufacturer. A few points on the care of the tablet machine may, however, be brought out in order to save the novice trouble and mishaps.

All compressing machines for tablet making consist essentially of a die and two punches, an upper and a lower. It is important that these be kept scrupulously clean and free from rust, nicks and scratches; for unless these parts be perfectly smooth it is impossible to get them to work properly. When not in use, they should be kept completely covered with vaselin or else immersed in liquid petrolatum, in order to protect them against rust. When required for use, the grease is removed from them as completely as possible by means of a soft cloth.

In putting the die and punches into the machine, it is best to put in the lower punch first, making sure that it has been pushed completely down into its socket. Then put in the die, so that the top of the die be exactly flush all around with the table of the machine. See to it that the face of the lower punch be exactly flush with the top of the die when the punch is at its highest point. Then insert the upper punch in its socket; and let it enter the die before locking it in place, so as to insure perfect alignment.

When die and punches are to be removed, take out the upper punch first, then the lower punch and die, which may come out suddenly and be injured by knocking against the upper punch if the latter be still in place.

When particles of the powder stick to the die or punches, they should not be scraped off with a hard instrument, as this is liable to scratch, but should be wiped off with a soft, slightly moistened cloth. To prevent sticking, a little talcum may be used, sprinkled over the powder and lightly mixed by stirring with a spatula.

When the upper face of the tablet splits off, we speak of "capping." To overcome this, ten per cent. of fat starch may be added to the powder. Should "capping" still occur, the amount of fat starch might be increased. "Capping" may also be due to the use of excessive pressure. It may furthermore be due to die or punches being worn or damaged. When this has occurred, the best thing to do is to get a new set of punches, or to have the damaged one refinished by an expert mechanic, preferably the makers of the tablet machine.

It would lead us beyond the scope of this work to give detailed directions for making tablets of all kinds. A pharmacist who has equipped himself with a tablet machine and has developed the ambition to make a general line of tablets[7] may be referred to Mr. Joseph R. Wood's book[8] on this subject.