LEAD. 
§ 827-] 
suppose, e.g., that a deceased person previous to death had partaken of 
game, and inadvertently swallowed a shot—if the analyst had not care¬ 
fully searched the contents of the stomach for solid bodies, but merely 
treated them at once with acid solvents, he would naturally get very 
decided lead reactions, and would possibly conclude, and give evidence 
to the effect, that a poisonous soluble salt of lead had been administered 
shortly before death. 
§ 827. Detection and Estimation of Lead. —A great number of 
fluids (such as beer, wines, vinegar, water, etc.), if they contain 
anything like the amount of one-tenth of a milligramme in 100 c.c., 
will give a very marked dark colour with SH 2 . It is, however, safest 
to destroy all organic matter by evaporating to dryness and incinera¬ 
tion at a very low red heat in a muffle ; the incineration should be 
fairly complete, for it has been shown that carbon retains lead with 
considerable tenacity.' 
If (in the usual course of routine research) a hydrochloric acid 
solution is obtained from the treatment or destruction of organic sub¬ 
stances by that agent, and lead sulphide (mixed possibly with other 
sulphides) is filtered off, any arsenical sulphide may first be extracted 
from the filter by ammonia, and any antimonious sulphide by sodic 
sulphide ; then the sulphide may be extracted by warm hydrochloric 
acid, which will leave undissolved such sulphides as those of copper and 
mercury. On diluting the liquid, and filtering at a boiling temperature, 
crystals of lead chloride will be deposited on cooling. 
In the case of sulphate of lead, which may be always produced in 
an ash from organic substances by previous treatment with sufficient 
sulphuric acid, one method of identification is to convert it into sugar 
of lead. To do this, it is merely necessary to boil it with carbonate 
of ammonia, which changes it into carbonate of lead; treatment 
with acetic acid will now give the acetate ; the solution may (if the lead 
is in very small quantity) be concentrated in a watch-glass, a drop 
evaporated to dryness on a circle of thin microscopic glass, and the 
crystals examined by the microscope ; the same film next exposed to the 
fumes of SH 2 , which will blacken it ; and lastly, the solution (which 
should be sweet) tasted. A crystalline substance possessing a sweet 
taste, and blackening when exposed to SH 2 , can, under the circum¬ 
stances, be no other substance than acetate of lead. 
By far the easiest method of identification is, however, to treat the 
sulphate with a solution of stannous chloride in hydrochloric acid. The 
sulphate of lead dissolves, and as the solution cools, crystals form, 
which glitter like micro-diamonds. These, when microscopically 
examined, are hexagonal plates, which vary but little in form ; they 
differ from the crystals of lead chloride precipitated by strong hydro¬ 
chloric acid, which vary in form, and are mostly rhombic. The 
