ON THE ADULTERATION OF ISINGLASS. 
239 
uncut, from the museum of the Pharmaceutical Society, and 
others obtained from the house of Simpson and Humphrey, 
were used in determining the characters of this substance. 
In making the corresponding determination with reference 
to gelatine, specimens were used of the cut and uncut gela- 
tine, as met with in commerce, including Nelson's opaque 
and transparent gelatine, and the French gelatine, commonly 
called grenatine. 
Action of water on isinglass and on gelatine.— -If cut 
isinglass be macerated in cold water, it will assume an opa- 
lescent appearance, becoming more opaque than it was pre- 
viously to its immersion. The shreds, although they swell 
and soften, will retain their integration. On examining thin 
slices under the microscope, they present the appearance of 
a fibrous structure. 2. If cut gelatine be macerated in cold 
water, it will assume a transparent appearance, this effect 
increasing with prolonged maceration. The shreds will 
swell up and soften, and ultimately become disintegrated. 
On examining a thin slice of the softened gelatine under the 
microscope, it does not present the appearance of a fibrous, 
but rather of a flaky, structure. 
Action of solution of caustic 'potash on isinglass and on 
gelatine. — 1. If cut isinglass be macerated in cold solution 
of caustic potash (liquor potassse of the Pharmacopoeia,) it 
will speedily become transparent ; and after a lapse of a few 
hours, if occasionally stirred with a glass rod, it will be dis- 
solved, forming a clear and colorless solution. After allow- 
ing the solution to stand for some time, a very slight floccu- 
lent precipitate will be deposited, which, in operating on 
twenty or thirty grains of the isinglass, will be scarcely per- 
ceptible. 1. If cut gelatine be macerated in cold solution of 
caustic potash it will become opaque ; even those specimens 
which were so, to a certain extent, previously, will assume 
increased opacity after their immersion. The gelatine will 
ultimately dissolve, as does the isinglass, but the solution 
will not be transparent, and after standing for some time, a 
