iS 82 .j 
Analyses of Books, 
237 
years ago were thought quite outside its scope. In certain 
cases — e.g., the determination of sulphuric acid — it even appears 
that the gravimetric method is inferior in accuracy as well as in 
despatch. The volumetric analyses of gases, a subject not 
touched upon in the first edition, is treated at very considerable 
length in the one now before us. 
Under the analysis of water we read that the method of esti- 
mating nitrogen as ammonia is substantially that described by 
the late W. A. Miller (“Journal of the Chemical Society” [2], 
iii., p. 125). We presume the author means to say “ the method 
of estimating that portion of nitrogen which exists in water as 
ready-formed ammonia.” The language he actually uses would 
seem to include the determination of organic nitrogenous matter 
according to the process of Wanklyn, Chapman, and Smith. It 
must also be remarked that the determination of pre-existing 
ammonia or ammoniacal salts by distillation with sodium car- 
bonate, and subsequent “ Nesslerising,” is popularly ascribed to 
the three chemists just mentioned. The author expresses himself 
very confidently — too confidently we fear — as to the trustworthi- 
ness of the means of determining the organic impurities in 
potable waters described in his Part VI. We are unable to share 
this confidence, and think that, so far at least, no perfedt process 
for water-analysis has yet been devised. We know at least one 
signal instance where two identical samples of water, or rather 
two portions of one sample, on being sent through distinct chan- 
nels to a very eminent chemist, gave results widely different, but 
in stridt accordance with that chemist’s known predilections. No 
chemical test seems capable of showing if nitrogen, whether de- 
termined by combustion or by conversion into ammonia, has 
been derived from a deadly or an innocent microbion. Water 
absolutely and permanently free from organic nitrogen is not 
found in Nature, and it is quite conceivable — or rather it is pro- 
bable — that the sample containing the smaller quantity may be, 
from its quality, the more deadly. If we may venture to sug- 
gest, the water analysis of the future will turn more on micro- 
scopic examination and on “ culture ” experiments than on 
stridtly chemical procedures. But progress in this direction is 
for the present barred to English chemists and physiologists. 
We do not see that the “ hydrosulphite ” process — the determi- 
nation of the quantity of free oxygen present in any sample of 
water by means of the hydrosulphite solution of Schiitzenberger 
and De Lalande — is mentioned. This process is certainly prac- 
ticable, but whether the free oxygen varies in regular inverse 
proportion to the organic impurities requires further examination. 
Our own observations leave the question doubtful, and we look 
forward with much interest to the results of others. 
One of the changes which volumetric analysis has undergone 
is the substitution of atomic standard solutions for those called 
empirical. We are not sure that this change is in all cases an 
