so 
MISCELLANY. 
the mercury is no longer perceptible. With 4 per cent., and even with 
2 per cent, of lead, a solid crystalline compound is obtained. In gene- 
ral the amount of lead does not exceed 1 per cent. In order to effect 
the purification of the mercury by protochloride of iron, 2 lbs. of mer- 
cury are triturated together with 2 oz. of Liq. ferr. mur. of 1.48 spec, 
grav., and as much water for ten minutes; then the solution of iron 
removed by decantation and washing with water, and the mercury 
deprived of its humidity by gentle heat. On trituration, the greater 
portion of the mercury runs together ; by suitable treatment with mu- 
riatic acid, the calomel may be separated from the mercury in the 
gray powder, and decomposed with protochloride of tin and muriatic 
acid. If the amount of lead exceed 1 percent., the operation should 
be repeated. — Ibid, from Archiv. der Pharm. 
Preparation of Uric Acid from Guano. By Dr. Bensch. — The guano 
is well boiled for several hours with common potash, slaked lime and 
a sufficient quantity of water ; the solution separated from the residue 
by a conical bag, evaporated until it forms a thick paste, and thrown 
whilst hot upon a linen cloth and pressed. The pressed mass is dif- 
fused through water, decomposed with common muriatic acid, and 
the coloured impure uric acid washed with water. The washed uric 
is dissolved in dilute solution of potash, and evaporated until the boil- 
ing fluid assumes the consistency of a thick paste, thrown upon a 
linen bag, and strongly pressed. The pressed urate of potash is boiled 
with 2 vols of water, constantly shaken, then rapidly pressed, and this 
proceeding repeated three or four times; this causes the mass to swell 
considerably; hence constant agitation is requisite top revent its being 
burnt. If a portion, when dissolved in potash and precipitated by 
muriatic acid, does not yield a perfectly colourless uric acid, the urate 
of potash is again completely dissolved in solution of potash, and treat- 
ed as above. 
Lastly, the perfectly white uric acid is dissolved in hot water, to 
which a little solution of potash is added ; the clear hot solution, when 
poured into muriatic acid, yields colourless uric acid. 
The mother-liquors are evaporated and treated as above, the purer 
solutions of potash being used to dissolve the potash salt in the more 
impure. 
By this method I obtained 2| lbs. of pure uric acid from 100 lbs. 
of guano. — Ibid, from der Pharm. und Chem. 
