128 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. [August 13,1S70. 
this not to have been the case; but that, on the contrary, 
every sample used contained adhering water, and one 
more than another; and further, that every sample might 
have lost ammonia, while none could have had it in ex¬ 
cess. Obviously, therefore, it has been wrong to take, 
as has been done, the mean percentage quantities of the 
constituents as the nearest approach to the quantities in 
the pure salt. 
I shall now endeavour to show that the several results 
obtained unequivocally indicate, when taken in conjunc¬ 
tion with each other, that the salt examined was a half¬ 
acid carbonate, having less than five atoms of water. All 
the samples, save the last, show but very slight evidence 
of loss of ammonia, and even in this the ammonia need 
only to have been 24-6 instead of 23'6 to be in the right 
proportion to the carbonic anhydride. All the samples 
were damp; but as the first sample yielded 8 per cent, 
more water on analysis than the second and third sam¬ 
ples, equally free from decomposition, but better dried, 
no other conclusion can be come to than that either the 
first sample was a very wet one indeed, or else that a 
more hydrated half-acid carbonate breaks up, while in a 
moist state, into water and a less hydrated one,—which 
no one contends for, and which, from the facts of my own 
analyses, I cannot admit. In the second and third sam¬ 
ples, the water is nearly 2 per cent, less than the calcu¬ 
lated quantity for five atoms; and yet both had prac¬ 
tically suffered no decomposition, and both were damp. 
How is it possible, therefore, from these results, to deduce 
for the salt the formula with five atoms of water ? In 
the fourth sample, the water is even 24 per cent, less 
than the calculated quantity; but then this sample was 
somewhat decomposed. It is not too much to suppose 
that, as the first sample contained 8 per cent, more water 
than the others, these, moist as they were, still retained 
2\ per cent, of moisture. And I contend that, had the 
drying been carried on uninterruptedly, instead of in 
four stages, as was done, and with due protection of the 
salt from the free action of the air, more water might 
have been absorbed from the wet salt, without such a 
loss of ammonia as would have rendered the indication 
of the analytical results ambiguous. Even, however, as 
they stand, the results indicate the salt with four atoms, 
in a slightly decomposed and moist state; and in this 
state they are described to have been. They contain, in 
this moist state, only 2 4 per cent, too much water for this 
formula. I consider, therefore, that Deville’s analyses in 
reality require the adoption of the formula with which 
my own analyses so closely agree. 
It may be added that, when considering the relations 
and analogies of this salt, a fifth atom of water is found 
to render its composition peculiar, if not abnormal. 
Chemical Behaviour .—I have little to say of the beha¬ 
viour of the half-acid carbonate under circumstances 
capable of affecting it. The change it undergoes into 
acid carbonate, when exposed to the air, is quite analo¬ 
gous to that undergone by the normal carbonate :— 
(C0 2 ) 3 (OH 2 ) 4 (NH^) 4 =3 C0 2 OHo NH 3 +OH 2 +NH 3 . 
It is the difficulty of preventing this change, which 
renders so very doubtful the accuracy of Rose’s analyses.* 
When heated, its crystals melt, and are decomposed. It 
is soluble in a little more than five parts of water at 15°; 
less water than this first becomes saturated, and then 
slowly decomposes the undissolved salt, leaving behind 
acid carbonate. Its solubility is, therefore, as nearly as 
can be stated, that of the acid carbonate it may be said 
to contain; 272 parts containing 158 parts of the acid 
carbonate, or about three-fifths of their weight. For the 
acid carbonate is soluble in 8 parts of water, and, there¬ 
fore, three-fifths of a part in about 5 parts. A solution 
* On allowing the crystals of half-acid carbonate to decom¬ 
pose in a limited quantity of air, Deville has observed crystals 
of acid carbonate form, which he thinks belong to a different 
system from that of the ordinary crystals of acid carbonate. 
( : Comptcs Rcndus,’ vol. xxxiv. p. 880.) 
saturated at 20° evolves sufficient carbonic anhydride to 
repel the stopper of a bottle containing it; and, gently 
heated, effervesces copiously. A saturated solution, 
cooled, gives good crystals of acid carbonate. It is also 
decomposed by spirit, acid carbonate being left undis¬ 
solved. Ammonia has, no doubt, an action upon it, com¬ 
pounded of its respective actions upon the normal and 
acid carbonates. In short, the half-acid carbonate seems 
to be intermediate in its other chemical properties, as it 
is in composition, to these carbonates. 
When the half-acid carbonate is obtained by treatment 
of the commercial carbonate with water, the mother- 
liquor from the crystals is equivalent in composition to a 
solution of normal carbonate, with or without a slight 
excess of ammonia. And Rose also found that the mo¬ 
ther-liquor from the crystals formed by his method was 
a solution of normal carbonate. From this somewhat 
remarkable fact the half-acid carbonate seems to be 
totally insoluble in a concentrated solution of normal 
carbonate. An explanation of this fact on another as¬ 
sumption will, however, be given in another part of this 
paper. 
I may here mention one fact of interest concerning 
crystals of the half-acid and normal salts, viz., that they 
appear to act on the glass, both English and German, of 
the bottles and flasks in which they are stored for some 
time, destroying the transparency of its surface. I have 
not observed the solutions of these salts to do so. 
PHARMACEUTICAL NOTES. 
BY ALBERT E. EBERT. 
Not the least duty of the pharmacist, though one more 
honoured in the breach than the observance, is his obli¬ 
gation to communicate to his fellows of the craft such 
improvements in manipulation, in apparatus, and in the 
convenient arrangement of his shop as his every-day ex¬ 
perience behind the counter must occasionally suggest. 
How much practical, desirable information is hid under a 
bushel by this sin of omission we can only conjecture; 
but if the thousands would communicate their personal 
experience, it cannot be doubted that a valuable fund of 
useful knowledge would accumulate. The following 
suggestions are made with no great claim for their origi¬ 
nality or importance, but, since they are based upon ac¬ 
tual experience, they may be of utility to others as they 
have been to us. 
Test-tubes, indispensable for their legitimate purpose, 
will often answer another useful end. For effecting so¬ 
lutions of small quantities of the alkaline or metallic 
salts, especially when the solvent is of a viscid nature, 
we have found the test-tube a valuable auxiliary,—more 
convenient in use than the mortar, less wasteful, and 
effecting the solution with greater dispatch. We pro¬ 
ceed by dropping the salt into the tube, adding a portion 
of the vehicle, and applying heat, with constant shaking 
of the tube. Solution quickly follows ; the warm liquid 
is added to the remainder of the vehicle, previously 
placed in the vial, and the whole is mixed by agitation. 
Of course, the dispenser will see that this method of 
procedure is not applicable where the quantity of the 
salt exceeds its solubility in the whole liquid at ordinary 
temperatures, as crystallization would occur. This rela¬ 
tion of salt to solvent is often met with, and then the 
only resort is to the mortar, in which the salt may be 
rubbed to powder before its mixture with the liquid, and 
the attachment of a “shaking label” to the vial. Solid 
extracts may be brought into solution by the same means 
with great facility. 
The moral effect of such a display of chemical ware 
before the admiring eyes of the patient may be consi¬ 
dered, in some rare instances, as equally beneficial with 
the product of the combined skill of the physician and 
pharmacist. 
In spreading plasters extemporaneously, convenience 
