84 Dr. Thomson on Arsenic. [Feb. 



4. Muriate of Magnesia. — No change at first ; but on heating 

 the mixtvue, a copious white precipitate fell. 



5. Muriate of Ahimina.\\yhite precipitates. Redissolved 



6. Alum. J by nitric acid. 



7. Nitrate of Lead. — A white precipitate. Redissolved by 

 nifric acid. 



8. Sulphate of Nickel. — An apple-green precipitate. Redis- 

 solved by nitric acid. 



9. Sulphate of Cobalt. — A dirty-red precipitate. Redissolved 

 by nitric acid. 



10. Nitrate of Silver. — A flesh-red precipitate. Redissolved 

 by nitric acid. 



11. Muriate of Tin. — A white precipitate. Redissolved by 

 nitric acid. 



12. Pernitrafe of Mercury. — A white precipitate. Redis- 

 solved by nitric acid. 



13. Frotosulphate of Iron. — A greenish-white precipitate. 

 Redissolved by nitric acid. 



14. Sulphate of Copper. — A bluish-green precipitate. Redis- 

 solved by nitric acid. 



15. Sulphate of Zinc. — A white precipitate. Redissolved by 

 nitric acid. 



16. Sulphate of Manganese. — A white precipitate. Redis- 

 solved by sulphuric acid. 



17. Muriate of Iridium. — Xo immediate change ; but on 

 heating the liquid, a brown precipitate fell. 



18. Sodamuriate of Bhodium. — No immediate change; but on 

 heating the liquid, a yellowish-white precipitate fell. 



ly. Nitromuriate of Platinum. — A light-brown precipitate. 

 Redissolved by nitric acid. 



20. \ilrojnuriate of Gold. — No immediate change ; but on 

 heating the liqyid, a yellowish-white precipitate fell. 



21. Muriate of Antimony. — A white precipitate. Redissolved 

 by muriatic acid. 



22. Tartar Emetic. — No change. 



23. Hi/drosulphurel of Soda-and- Antimony. No change. 



it now only remains to determine the composition of this salt. 

 I attempted in vain to determine in Avhat proportion the acid and 

 base unite by saturating the acid with the alkali, or vice versa, 

 noting the quantities of eaclr employed. I could not determine 

 when I had reached the requisite point of saturation, as the 

 liquid still continues to act upon vegetable colours when that 

 point has been reached. Fortunately, the analytical method in 

 the present case is attended with little difficulty. 



Fifty grains of the ciystals, by cautious exposure to a heat 

 slowly raised to 550°, lost 27-25 gr. of their weight, which I 

 consider as the water of crystaUization of the salt. When the 

 same weight of salt is exposed to a red heat, it sustains a loss of 



