PRECIPITATION OF METALS, 
215 
not be made by apothecaries in compounding prescriptions of 
physicians or surgeons; they are bound to the pharmaco- 
poeial process, and it would be great impropriety in them to 
substitute any preparation of a more active nature than is 
there indicated, unless with the full knowledge and approba- 
tion of the prescriber. 
Dublin Journal of Medical Science, May, 1839. 
ART. XXX.-ON THE PRECIPITATION OF THE PRINCIPAL 
METALS, BY MEANS OP SULPHURETTED HYDROGEN, 
FROM SOLUTIONS ACIDIFIED WITH HYDROCHLORIC 
ACID. By M. Hugo Reinish. 
It has been hitherto believed that the salts of zinc, 
iron, manganese, cobalt, and nickel, were the only combi- 
nations not precipitated by sulphuretted hydrogen, from 
strongly acid solutions, whilst all other metals were thrown 
down and changed into sulphurets, even from solutions very 
strongly acid. I undertook a series of experiments for the 
purpose of ascertaining, the correctness of this opinion, and 
discovered that many metals, such as lead, tin, and platinum 
were not precipitated by sulphuretted hydrogen, when their 
solutions were strongly acidified, especially with hydro- 
chloric acid. 
If one part of the neutral acetate of lead be dissolved in 200 
parts of water, and to a portion of this solution, 25 per cent, 
of its weight of hydrochloric acid, of the density of 1.168 be 
added, there will form, at first, a small precipitate of chloride 
of lead, since this salt is but slightly soluble in hydrochloric 
acid. If afterwards we pass through the liquid a current of 
sulphuretted hydrogen, no precipitate will be perceived ; 
but if a few drops of this solution be let fall into water, an 
abundant precipitate of sulphuret of lead will immediately be 
formed. Hence it is very possible that in many analyses a 
