122 Scientific Intelligence. 
lium as a white curdy quickly-subsiding precipitate, which requires 50 
rts of boiling water and 200 parts of cold water for its solution, and is 
ess soluble in water containing chlorhydric acid.—Jodid of potassium 
(next to sulphid of ammonium the most sensitive reagent) gives a | 
yellow precipitate of iodid of thallium, which appears to be slightly — 
soluble either in water or excess of the reagent.—Bichlorid of platinum — 
throws down a pale orange precipitate of platinchlorid of thallium which 
is slightly soluble in water and is decomposed on ignition, evolving chlo- 
tral analysis. The spectrum is characterized by a single bright green 
line coincident with Bad. This line is however usually perceptible for 
ut a moment, owing to the volatility of the thallium compound, and 
hence its intensity and duration do not safely indicate the richness im 
thallium of pyrites, flue-dust, &e. fe 
Of crude sulphur a piece as large as a pea is nearly burned away ond 
platinum loop and the residue is examined in the spectroscope; or better, 
_ the sulphur is mostly dissolved by means of sulphid of carbon, and what 
remains is tested spectrally. In pyrites, flue-dust, and lead-chamber 
sediment, it may be usually detected at once by the spectroscope. . The 
sublimate procured by strongly heating finely pulverized native sulphids 
in a closed tube, often gives the reaction when none can be obtained — 
directly from the sulphids themselves. 8. Weal 
AnatyticaL CHEMIstRy.— 
10. Estimation of Sulphuric Acid in salts of the alkalies.—It is well 
known that precipitated sulphate of baryta may retain alkaline salts in 
consta 
