54 H. Wurtz on the Indigo Test. 
abe color (protochlorid of platinum) no precipitate being — 
formed. 
Bichlorid of tin, made by passing chlorine gas through a solu 
tion of the  rotochlorid to saturation, adding some chlorohydric 
acid, ev: to dryness and heating the residue until it 
volatilized pre in white fumes, to expel all excess of chlo- 
e€; gave a solution which bleached in igo readily and copi- 
ais even in the cold. Acidulation with hege acid did 
not affect the action. 
ure arsenic acid, having been ey ted in solution twice with 
chlorohydric acid to ensure absence of is acid, left a crystal- 
line residue which still contained much arsenic ¢ acid, for its solu- 
tion gave with nitrate of silver the brick-colored recipitate, but 
whic ae see also Wooly dre mre in some form 
ecessary to pe that b piketanons which 
évaleee chlorine, jodine or bromine, with muriatic acid, will also 
indigo, ‘such as KO, BaO?, Ce?03, the chromates, the 
and salts of the sesqwioxyd of manganese, manganates 
Se Pe onganates, chlorates, perchlorates, todates, bromates, deut- 
nit, of lead and the sesquioayds of nickel and cobalt, 
A mixture of ee of manganese with dilute sulphuric 
acid bleaches very stron, 
ere are a few aha Scar which interfere, although in 
another way, with the reaction. These are those bases whic 
give Eaeepiates with the sulphuric acid of the indigo solution, 
as baryta, strontia, lime, and. oxyd of lead. Ppa  Drecipitates, 
h 
'y successful in every case. Tt consists of an 
the a of Dr. Gibbs Sich br up ob- | 
in applyi 
