322 Notices respecting New Books. 



tioii was drawn to the experiments for the determination of the 

 velocity of sound made in the arctic regions under the superin- 

 tendence of Captain Parry, by the reference made to them in 

 Mr. Earnshaw's paper " On the Theory of Sound," in the 

 Transactions of the Royal Society (Part 1. 1860, p. 139). It is 

 stated that several times in the experiments made on February 9, 

 1822, the word of command to fire was heard after the report of 

 the gun ; and though the same circumstance was not remarked 

 on other days, it is to be said that on that day the number of 

 experiments was greater than on any other, the distance was in- 

 termediate to what it was on most of the other days, and the air 

 was still and barometer low. Taking all circumstances into 

 account, the experiment seems to establish the fact of an actual 

 difference of rate of propagation in waves of different intensities. 

 Cambridge, March 21, 1862. 



XLV. Notices respecting New Books. 



A Manual of Chemistry, Descriptive and Theoretical. By W. Od- 

 ling, M.B., F.R.S. Parti. London: Longman and Co. 1861. 



THE Unitary notation of Laurent and Gerhardt, although it has 

 made many disciples, does not as yet possess a complete lite- 

 rature of its own. It is true that there constantly appear, in Bri- 

 tish and foreign scientific journals, memoirs in which the unitary 

 formulae and an appropriate nomenclature are used. Yet although 

 this has been the case for several years, and many fresh converts 

 from among the most eminent chemists have joined the new sect, 

 the doctrines of Gerhardt, with the modifications and additions made 

 from subsequent experience, have not been embodied in a series of 

 text-books adapted for the instruction of the young student, nor of 

 works of reference for the more advanced. This is the more remark- 

 able since it seems almost customary for every professor of che- 

 mistry to write a manual of his science, which he can oblige his own 

 pupils to buy, even if he is unable to persuade the scientific world 

 to do so. Nine out of every ten such works could well be spared : for 

 they resemble one another very closely ; and even of some of those 

 whose success was at first merited, later issues have retained old 

 fallacies and omitted newly- discovered facts ; for when will chemical 

 authors cease to talk of sulphuric and oxalic acids as monobasic, and 

 to introduce these bodies quite commonly into descriptions and equa- 

 tions as SO 3 and C 2 O 3 ? But we are in real want of one complete 

 set of treatises in which the various branches of chemical science 

 proper shall be treated systematically according to the new view ; and 

 we welcome the first instalment of Professor Odling's contribution 

 to the series. 



As necessary chemical works, we may suggest the following: — 

 1 . A short, simple, introductory book explaining the scope and lan- 

 guage of chemistry, and describing fully the way of performing a 



