12 
DR. HOSKINS ON THE DECOMPOSITION OF CALCULI, 
five drops of pure saccharic acid, and dissolved in a fluid ounce of distilled water, 
formed a bland liquid without any astringency, although it possessed slight acid reac- 
tion. It acted with rapidity on various specimens of phosphatic calculi, forming 
around each, at the moment of immersion, the dense nebula formerly described, 
from which a white precipitate subsided. Chemically speaking, this was the most 
active agent yet experimented with, whilst its sensible character was so mild as to 
be tolerated with perfect impunity by the urethral and conjunctival membranes. 
The following experiments, selected from a great number of others, to the same 
effect, will suffice to show the results of the action of this nitro-saccharate solution 
on human phosphatic calculi. 
Experiment I. — Seven fragments of various sizes and figures, taken indiscriminately 
from a collection of phosphatic specimens, were placed in distilled water until air- 
bubbles ceased to be disengaged from them : they were found to weigh collectively, 
after being allowed to drain for a minute or two on bibulous paper, one hundred 
grains. 
These fragments, each suspended by a horse-hair, were placed in ten fluid ounces 
of the above-mentioned nitro-saccharate solution for twenty-five minutes, during 
which time the temperature of the fluid was maintained at 98° Fahr. They were 
then removed and plunged into ten ounces of fresh solution, of the same strength 
and temperature, for a quarter of an hour. In both cases, copious precipitation took 
place from each fragment, and accumulated at the bottom of the glasses. The cal- 
culi were then removed, drained for a few minutes on filtering paper, and, on being 
re-weighed, were found to have lost twelve grains*. 
The two portions of solution, together amounting to twenty ounces, were then 
passed through a filter ; and the precipitate, after being washed and carefully dried, 
was found to weigh eleven grains. A small quantity of it, heated alone on charcoal 
by means of the blowpipe, gave indications of the presence of phosphate of lead. 
In order, however, to determine the nature of the acid contained in the lead precipi- 
tate, another portion of it was dissolved in dilute nitric acid ; to this solution was 
added a drop or two of nitrate of silver, and on being cautiously neutralized by weak 
liquid ammonia, a yellow precipitate, characteristic of the presence of phosphate of 
silver, made its appearance -f~. 
A third portion of the dried precipitate was mixed with borax, and fused by the 
blowpipe on charcoal ; the bead thus formed was transfixed by a fine needle, and 
strongly heated in the interior flame ; on being broken after cooling, it was found to 
* The greater the extent of surface, the greater, generally speaking, will be the amount of decomposition, 
so that agents of this kind will, I trust, come with great effect to the aid of lithotriiy. 
f I may perhaps be permitted to remark, that in order to render this test determinate, the following precau- 
tion is necessary. If the assay be dissolved in dilute nitric acid, weak liquid ammonia must he used for neutral- 
ization, otherwise no yellow precipitate will be formed. On the other hand, if strong nitric acid is used for 
solution, it must be neutralized by strong liquid ammonia. In both cases the ammonia must be added cautiously, 
for an excess, however small, destroys the yellow colour of the precipitate. 
