204 
the liquid before distillation, instead of permitting all the 
aluminium to be dissolved, as in Mr. Chapman’s original 
modification of Schulze’s process. In the chapter on vola- 
tile organic matter, it is pointed out that on distillation of 
a water with potassic hydrate, there passes over, together 
with the ammonia, some combined nitrogen, probably in 
the form of organic bases, and a process is described for 
its estimation. The method of estimating minute traces 
of lead by comparison of the coloration produced by 
sulphuretted hydrogen water in dilute standard solutions 
of lead with that obtained by the same reagent in the water 
under examination is not new, for we remember having 
seen the experiment illustrated in Dr. Hofmann’s lectures 
at least fifteen years ago. The previous removal of oxi- 
dising agents by sulphurous acid is, nevertheless, a useful 
addition. In the chapter on the purification of water, an 
ingenious experiment is described to show that separation 
of suspended matter by filtration through sand and 
similar substances is really due to subsidence within the 
interstices of the filter. 
As in the first edition, we find no mode of estimating 
sulphides or the gases dissolved ; nor does the treatise 
contain any indication of the success of the application 
of the ammonia process in the examination of sea water; 
it may be answered that the title of the book only refers 
to potable waters, but then we are at a loss to explain the 
appearance of some experiments on sewage. 
It is much to be regretted that the present editor has 
thought fit to reprint the preface to the first edition, and 
also the appendix, which consists of nothing but an attack 
on Frankland and Armstrong’s process. ‘These entail on 
us the necessity of noticing this treatise at much greater 
length than the positive information contained in it would 
justify ; for if the statements set forth were passed over 
without remark, it might seem as if the untrustworthiness 
of the process were acknowledged by allchemists,and doubt 
thrown onthe accuracy and value of the reports issued by the 
Registrar General. The authors state in the preface to 
the first edition that it requires great length of time and 
great skill to execute it. This may be true, but the vast 
advantages which it possesses over the old processes 
amply compensate for the additional trouble. The 
manipulation, though delicate, is not, we are given to 
understand, beyond the powers of an average first year’s 
student, at least when he is not influenced by a precon- 
ceived distrust in the efficiency of the process, or by a 
desire to do things with as little trouble as possible. It 
was not quite fair for the authors to state, two months after 
the publication of the process, that chemists in general 
agreed with them as to its invalidity. They should have 
remembered that “chemists in general” are not such 
rapid workers as Messrs. Wanklyn and Chapman, and 
would wish for more time to give a definite decision on 
the capabilities of a process so entirely new. The ap- 
pendix consists of a note read by the authors before the 
Chemical Society. They commence by stating that they 
do not consider the complete conversion of organic nitro- 
gen into ammonia by their method as being essential to 
its applicability for determining the relative quality of a 
water, and that they rely simply on the constancy of the 
ratio between the amount of albumenoid substance in 
the water and the quantity of ammonia produced. This 
NATURE 
[Aug. 11, 1870 
is a retractation, though not a very straightforward 
one ; for in their first published account of the process 
it was stated that all the nitrogen was evolved as am- 
monia. But it would be well to ascertain if this ratio 
is really constant, for although this may be the case 
with white of egg, is it not almost too much to assume 
that the nitrogenous organic matter present in natural 
water acts in the same manner as albumen, when we 
are quite ignorant of its proximate constituents? If 
the quantity of ammonia always bears a certain relation 
to the organic matter, and if this ratio is known, the 
determination of the nitrogenous impurity is merely a 
matter of calculation ; but is it not a fact thatsome bodies, 
when treated according to the author's process, evolve 
more ammonia, in proportion to the amount of nitrogen 
they contain, than do others? The experiments on strych- 
nine, narcotine, and quinine sulphate, published by Frank- 
land and Armstrong (but not commented on by our 
authors), show this to be the case. But in their published 
papers, Messrs. Wanklyn and Chapman admit that the 
quantities of “albumenoid ammonia” from the following 
compounds are far from uniformly proportional to the 
amount they contain, thus :— 
Urea and Picric acid gaye no albumenoid ammonia 
Creatine gave % of its nitrogen as albumenoid ammonia 
Caffeine ty 4+ $5 59 
Uric Acid ,, about ¢ % 35 
Albumen *, t s ws 
Morphine & 11 orbery A 
organic substances! 7 2 ” 
Hippuric acid and 7| 
other organic sub-) all x 5 
stances 
Next follows a list of Frankland and Armstrong’s 
results, in which the differences of the quantities of 
carbon and nitrogen obtained by experiment and calcu- 
lations are pointed out. But it should be remembered 
that in these experiments the substances were weighed 
instead of being measured in standard solution, and that 
these solids were first dissolved and the solutions evapo- 
rated in order to perform the combustion of the residue. 
It is afterwards deduced from this same list that the 
error is inherent in the process, as the results are not 
better when the amount of organic matter is reduced ; 
but with this reduction the liabilities of error in weighing 
increase. If this discrepancy were really caused by the 
imperfection of the process, we should expect to find 
great variation in the quantities of nitrogen obtained in 
actual analyses of waters, but in the list of forty nitrogen 
determinations given in Frankland and Armstrong’s 
paper, the numbers vary from o’ooo to 0'068 per 100,000, 
or, as our authors would express it, from o to 0°68 milli- 
grammes per litre, whereas they accuse the process as 
being liable to produce an error of no less than 1:29 
milligrammes per litre. The following extraordinarily 
opportune accident has happened during the month of 
May, and from the results we shall be able to obtain an 
indication of the concordance of the numbers arrived at 
by Dr, Frankland’s process. In the Registrar General’s 
report it will be seen that the water supplied by the Grand 
Junction Company was drawn at the cabstand in Wood- 
stock-street, whilst a sample of water was taken at 14, 
Lancaster Gate, under the impression that it came from 
the works of the West Middlesex Company. Now, to our 
