80 ESSAY V. 



SECTION XXXVII. 



Half an ounce of powdered manganese mixed with 2 

 drms. of pounded sulphur were exposed to distillation in 

 a glass retort. A part of the sulphur rose to the neck of 

 the retort, and some of the volatile acid penetrated through 

 the lute ; at last the retort melted. After the residuum 

 was cold, it weighed 5 drms., and appeared of a yellowish 

 grey colour. It dissolved in spirit of vitriol with effer- 

 vescence and with an hepatic smell; when it was filtered, 

 some sulphur remained on the filter. It is insoluble in 

 water. Upon calcination in the open air, the sulphur was 

 volatilised, and the mass assumed a brown colour. After 

 this process a good deal of the mass dissolved in water and 

 shot into crystals, which were exactly like those of Sec. xxn. 

 The insoluble residuum, being calcined with more sulphur 

 in the same manner, was at last entirely reduced to such 

 crystals. This has also been observed by Mr. Westfeld ; 

 but he supposed them to be alum, to which I can by no 

 means assent. 



SECTION XXXVIII. WITH NITRE AND FIXED ALKALI. 



(a) Nitre triturated with manganese to a fine powder 

 and strongly calcined in a crucible loses its acid, and the 

 manganese combines with the alkali, forming a dark green 

 mass, which is soluble in water, communicating to it a green 

 colour. The colour is in reality blue (Sec. xiv. (4)) ; for, 

 after the solution has been kept for a few days in close 

 vessels, a fine yellow powder precipitates by degrees, which 

 for the greatest part is nothing but crocus martis, and the 

 solution afterwards turns blue. (&) In such a solution the 





