i879-] 
Notices of Books . 
251 
The Appendix is not the least valuable part of the book : it 
contains a number of useful hints as to glass-working, fusing 
platinum wires into glass, and so on. Finally, a list of the ap- 
paratus and materials necessary for experiments in sound and 
waves concludes a volume which we cordially recommend to the 
notice of all students of physical science. 
A Dictionary of Chemistry and the Allied Branches of other 
Sciences. By Henry Watts, F.R.S. Assisted by Eminent 
Contributors. Third Supplement, Part I. London : Long- 
mans and Co. 1879. 
This very valuable and standard work, which is without doubt 
the most exhaustive Dictionary of Chemistry in any language, 
furnishes, by the aid of its Supplements, a complete record of 
chemical research, within a short time of its appearance in the 
journals of scientific academies. Research is so abundantly on 
the increase that this closely-printed volume of 838 pages forms 
only the first half of the Third Supplement. The second half 
will appear before the end of this year, and will bring down the 
record of chemical discovery to the end of 1877, including, how- 
ever, the more important discoveries of 1878. 
Among the noticeable articles in Part I. we may mention 
Dr. Mills’s account of Cumulative Resolution, Dr. Thorpe on 
Flame, and Mr. Warington on Barley and on Forest Trees. 
But the great feature of the volume is, without doubt, the very 
exhaustive article — presumably by the Editor — on the Benzenes 
and Benzoic Acids, extending over more than 150 pages. This 
includes an account of Korner’s elaborate researches on the 
Orientation of the Benzene Derivatives, published in the 
“ Gazzetta Chemica Italiana,” and now for the first time made 
known to English readers. To this subject we venture specially 
to diredt the attention of chemists, as one which is well worthy 
of their complete consideration. 
The subject of “ Cumulative Resolution ” (a term proposed by 
Dr. Mills) has been developed by Wurtz, Watts, and Mills. 
The adtion is defined as “ the combination of a substance, or 
mixture of substances, with itself n times, a particular portion 
of it being lost each time, according to some fixed law. Thus, 
bismuthic nitrate, when decomposed by a gradually increasing 
quantity of water, yields a series of bodies, which are less and 
less nitrogenous, and more and more bismuthic. Having regard 
to the denitration alone, we write — 
n(Bi 2 0 3 .3N 2 0 5 ) — ( n — i)N 2 0 5 =Bi 2n 0 3M ,N 4n + 2 0 IOW +5, 
and by giving various values to n> from o to 00, we shall obtain 
the formulas of all possible compounds between Bi 2 0 3 .3N 2 0 5 and 
