Chemical Science, 4^1 



29. Separation of Stroniia from Baryta. — ^The formation of 

 these earths into muriates, and the separation of them by the 

 action of alcohol, in consequence of the solubility of the strontia 

 muriate, and the insolubility of the baryta salt, is well known. 

 M. Kastner remarks, that to be a good process the salts must be 

 anhydrous, and then treated with alcohol at 84° (183° Fah.) Care 

 must also be taken that the alcohol is guarded so that it cannot 

 attract water from the atmosphere.— fiuW. Univ. A. xiii. 134. 



30. Sulphate of Potash and Copper. — ^When equal quantities of 

 sulphate of potash and sulphate of copper are mixed, a particularly 

 clear green precipitate is gradually formed, which Vogel considered 

 as a subsalt. Having been analyzed by Brunner, it appears to 

 consist of 



Oxide of copper . . . 39.23 



Potassa . . . . 12.12 



Sulphuric acid . . . . 39.70 



Water 8.94 



100.00 



31. Preparation of Cinnnbar in the humid way, — Kirchoff first 

 shewed that by commingling and triturating mercury, sulphur, and 

 potash together, and applying heat, cinnabar might be obtained. 

 But the process was uncertain, and gave variable quantities of 

 vermilion. The following is a process recommended by M. Brun- 

 ner: 300 parts of mercury, 114 of sulphur, 75 of caustic potash, 

 and from 400 to 450 of water are used. The mercury and sulphur 

 are first triturated together for from three hours to a whole day, 

 according to the quantities used. When the mixture is homoge- 

 neous the solution of potash is added, the trituration continued, 

 •and the mixture heated in a vessel of earth, porcelain, or on a large 

 scale, of iron ; at first the stirring must be constant, afterwards 

 firom time to time. The heat should be sustained at 113° ; it should 

 never pass 122°. The liquid should not be allowed to diminish by 

 evaporation, but be made up. After some hours, the mixture will 

 acquire a reddish-brown colour, and then great care is required ; 

 the mixture must not pass 113° If it becomes gelatinous, a little 

 water should be added ; the mixture of sulphur and mercury should 

 always be in a pulverulent form in the liquid. The colour becomes 

 more and more brilliant, and at times increases with astonishing 

 rapidity : when it has attained its highest intensity the vessel is to 

 be taken ofi" the fire, but still to be retained warm ft)r several hours. 

 The time necessary for the application of heat appears to be directly 

 as the quantity operated upon. If the proportions above be in 

 grammes (about 15 J grains each), the red colour will appear in 

 about eight hours, and the operation be finished in ten or twelve 

 hours. 



The cinnabar is then to be washed^ and the small quantity of 



2F2 



