Punctuation and spelling were made consistent when a predominant preference was found in this book; otherwise they were not changed.

Simple typographical errors were corrected; occasional unbalanced quotation marks retained.

Ambiguous hyphens at the ends of lines were retained; occurrences of inconsistent hyphenation have not been changed.

Redundant chapter titles have been removed.

Text sometimes expresses fractions with a dash instead of a slash. That notation has been retained here.

The name “Van ’t Hoff” always was misprinted as “Van’t Hoff” in the original book. That misprint has been retained here.

Page 46: The original book used “Zu” as the symbol for zinc.

Page 122: “entirely changed by” was printed as “charged”; changed here.

Page 139: “barometric” was printed as “barometic”; changed here.