124 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS 
[August 12, 1671. 
Use of the Xcssler reagent. —Into a cylinder made of 
colourless glass, and marked so as to be a 50 cubic centi¬ 
metre measure, put the distillate which, you desire to test 
for ammonia. Add cubic centim. of ‘ Nessler re¬ 
agent,’ which will produce a yellowish-brown colora¬ 
tion. Observe the depth of the colour. On a white 
piece of paper, side by side with the cylinder containing 
this coloured liquid just mentioned, place a second 50 
cubic centim. cylinder. Into this second cylinder put 
pure distilled water, and add to the pure distilled water 
some standard dilute ammonia liquid—as many measures 
cf the standard ammonia as you judge to be requisite. 
Add I 5 cubic centimetre of Nessler reagent—a colora¬ 
tion will result—compare the colour with the colour of 
the liquid in the first cylinder. If the colours are equal, 
write down the quantity of ammonia you have added, 
and that will be the quantity contained by the 50 cubic 
centim. of distillate. If the colours are not equal, make 
another trial with a different quantity of standard am¬ 
monia, and so on until you get equal coloration. 
The strength of the standard ammonia is such that one 
<cubic centimetre contains ITOOth milligramme of ammonia. 
It is made by dissolving 0-315 gramme of chloride of 
ammonia in one litre of distilled water, and then mixing- 
that solution with nine times its volume of pure distilled 
water. 
The operation of Nesslerizing; as it is called, that is, 
the operation just described, is not difficult, as the many 
chemists who are in the habit of practising it have abun¬ 
dantly testified. There are a few little points requiring 
attention; thus, a few minutes must be allowed to elapse 
before reading- off the colour; the liquid must be cool, 
the distilled water must be very free from ammonia, etc. 
The distilled water used for Nesslerizing is best prepared 
by the operator himself. A fair river water being taken, 
is set to distil; at first ammoniacal water will distil 
over, but after a time water free from ammonia will dis¬ 
til, and this must be tested, and then carefully preserved 
for use.* 
The following arc some examples of milk-analyses by 
the ammonia process ;— 
Milk yielding 12-92 per cent, of solids, and 8 per cent. 
of cream. 
Quantity of Milk taken. Quantity of NH 3 obtained. 
Exp. I. . . .100 milligr.0-27 milligr. 
Exp. II.... 50 „ .... 0-13 „ " 
Exp. III. . . 50 „ .... 0-13 „ 
Milk which appeared to have been somewhat skimmed, 
but not watered. Solids, 11-42 per cent. 
Quantity of Milk taken. Quantity of NH 3 obtained. 
Exp. I. ... 50 milligr.0-135 milligr. 
Exp. II. ... 100 „ .... 0-255 „ 
Slightly-watered Milk. Solids 10-20 per cent. 
Exp. I. . 
Exp. II. . 
Exp. III. 
Quantity taken. Quantity of I4H 3 obtained. 
• • 50 milligr. 0-095 milligr. 
• • 50 „ .... 0-095 ,, 
• • 100 „ .... 0-022 „ 
Highly-watered milk. Solids, 6-18 per cent. 
_ Quantity taken. Quantity of NH 3 obtained. 
Exp. I. . . . 50 milligr.0'075 milligr. 
Highly-watered milk. Solids, 8-10 per cent. 
Quantity taken. Quantity of NH 3 obtained. 
Exp. E ... 50 nnlhgr. 0-070 milligr. 
Expressed in a tabular form:— 
Percentage 
Solids in Milk. 
Percentage of Ammonia 
1 . 
» • • 
. . 12-92 . 
..... 0-27 
II. 
• • • 
. . 12-92 . 
.... 0-26 
III. 
• • • 
. . 12-92 . 
.... 0-26 
I. 
• • • 
. . 11-42 . 
.... 0-27 
II. 
• • • 
. . 11-42 . 
. . . . 0-255 
I. 
• • • 
. . 10-20 . 
.... 0-19 
* For further details I would refer to the book on Mater- 
analysis, by Chapman and myself. 
Percentage Solids in Milk. Percentage of Ammonia. 
II. . . . 
. . 10-20 . 
.... 0-19 
III. . . . 
. . 10-20 . 
.... 0-22 
I. • • • 
. . 6-18 . 
. . . . 0-15 
II. . . . 
. . 8-10 . 
.... 0-14 
In order to translate these results into percentages of 
caseine contained by the different samples of milk, it has 
to be borne in mind that 6*5 parts of ammonia correspond 
to 100 parts of caseine. The ammonia, therefore, when 
multiplied by 100 and divided by 6-5, indicates the 
caseine. In conclusion, the ease and rapidity of these 
determinations may be referred to. In half an hour an 
analysis of milk by the ammonia process may be easily 
made.— The Milk Journal. 
THE MODERN ASPECTS OF THERAPEUTICS. 
BY WALTER G. SMITH, M.D. 
(Concluded from page 106.) 
But the most decided stop in this direction has been 
made by Drs. Crum Brown and Eraser, in their im¬ 
portant papers “ On the Connection between Chemical 
Constitution and Physiological Action ” (1868-69). By 
introducing a known chemical change into the constitu¬ 
tion of a physiologically active substance, without break¬ 
ing up its molecule, they have shown that the physio¬ 
logical action of the substance may be completely altered, 
and, in fact, inverted in kind. 
They have examined with groat care the physiological 
action of the salts of the ammonium-bases derived from 
eight of the better known alkaloids, and their results 
lead to the suspicion that chemical condensation ( i. e. sus¬ 
ceptibility of addition) is in some way connected with 
physiological activity, and that saturated bodies («.<?., 
whose condensation = °) arc inert, or nearly so. Thus 
by the addition of iodide of methyl to the non-saturated 
base strychnia, the poisonous activity of that alkaloid is 
diminished at least 210 times, and a quantity of iodide of 
methyl-strychnium, containing 21 grs. of strychnia, can 
be given to a rabbit with impunity. These observations 
arc of the highest value, though .at present they must be 
considered as but foretastes of what is to come, and it is 
remarkable that almost immediately after, two French 
physiologists, MM. Jolyet and Cahours published results 
corresponding in almost every respect with those of 
Brown and Eraser. 
Hr. Richardson has done good work in the field of 
anaesthetics in their c-hemico-physical relations, and he 
has brought out the curious and interesting fact that, in 
the alcohol group, the anaesthetic effect has a definite 
connection with the chemical composition of the alcohol, 
the anaesthesia rising in proportion to the number of 
atoms of carbon; for example, contrast the action of 
ethylic alcohol, containing C 2 , with amylic alcohol, con¬ 
taining Cl. It is observed also that definite changes are 
produced by the addition or substitution of new elements 
or radicals, such as H, Cl, I, CUE, etc., and when the 
chemical relationships between different bodies are more 
thoroughly understood, we may eventually be able to 
deduce d priori the physiological action of a body from 
its known chemical history. 
Dr. Rabuteau, who has made many contributions to 
physiological chemistry, believes that he is justified by 
his investigations in propounding, as a general law, that 
“the metals are more active physiologically, according- 
as their atomic weights are more elevated, or, what is 
the same thing, as their specific heats are lower,” c.g. 
Na, K, and Tl. The diatomic metalloids conform also 
to this atomic law, but the monads, cui'iou3ly, are 
governed by a law which is the reverse of this. Thus 
F, Cl, Br, and I, is the order of physiological activity 
of the halogens, and this is precisely the inverse order 
of their- affinity for O. 
These illustrations are, at least, sufficient to shadow 
forth the assistance, qualitative and quantitative, which 
we may expect from physical and chemical science, and 
