
ON THE ADULTERATION OF ISINGLASS. 235 
immediately change color, and will become of a brownish- 
black more or less deep. 
As it is impossible to use paper, linen or cotton, some 
woollen tissue, for instance a white merino, may be employed. 
After having dipped the merino for three or four minutes in 
an aqueous solution of bichloride of tin (the oxymuriate of 
commerce, SnCl 2 ,5HO,) made with 100 grms. of bichloride 
and 200 grms. of ordinary water, let the liquid drain off, 
dry the merino in a piece of the same substance on the 
water-bath, and the reagent is prepared. It is cut into 
strips, like the ordinary test papers. 
By means of this chlorinated merino, the physician will 
be able, without the least difficulty, to determine whether 
the urine of a patient contains an appreciable trace of sugar. 
It will be sufficient to pour one drop of the urine upon one 
of these strips, and to hold it over a piece of incandescent 
charcoal, the flame of a lamp or of a candle, to produce in 
an instant a very visible black stain. The sensitiveness of 
the test is enormous; 10 drops of a diabetic urine, added to 
100 cubic centimetres of water, furnish a liquid which turns 
the chlorinated merino completely brownish-black. Ordi- 
nary urine, urea and uric acid are not colored by the chlo- 
ride of tin. — Chem. Gazette ^Jlpril 15, 185G, from Comples 
Ben d us } M?,rch 18, 1S50. 
ART. LVL— ON THE ADULTERATION OF ISINGLASS. 
By Theophilus Redwood, Esq., 
Professor of Chemistry and Pharmacy to the Pharmaceutical Society. 
I have recently been engaged in the examination of spe- 
cimens of some of the isinglass now met with in commerce, 
which, from the price at which it has been sold, was sus- 
pected to be adulterated. The subject, previously to its 
