[ 19 3 



brown-coloured cloud, with a precipitate of the fame 

 colour. 



A (hilling and a fixpence, put into two different 

 tea-cups, were prefently tarnifhed, and became of a 

 very dark colour. 



Each drop of a folution of iilver in fpirit of nitre, 

 occafioned a dark brown or blackifh cloud, and fell 

 in form of a black precipitate to the bottom of the 

 glafs. 



Some very white faccharum faturni turned imme- 

 diately black, and precipitated in form of a black 

 powder to the bottom of the glafs. 



Four pounds feven ounces and fix drachms, (or 

 lxxi ounces vi drachms) were poured into a flone 

 bafon, which was put on a land heat to evaporate 

 with a flow fire. 



As foon as the water became warm, it loft its 

 ftrong fulphureous fmell, and there appeared fome 

 flakes of a dark brown light earth, which dropt to 

 the bottom. After about one half was evaporated, 

 a very thin pellicle was obferved on the furface, 

 which precipitated to the bottom, and when it was 

 reduced to about a pint ( lib. i. ), it was filtrated 

 through paper, and about 2 \ gr. of a dark grey 

 infipid fediment was feparated. This fediment 

 was compofed of the dark coloured earthy flakes, 

 which were obferved fo foon as the water had become 

 warm, and of a fmall quantity of a whitifh, infipid 

 gritty matter, which had formed the very fine thin 

 pellicle. Some of it being thrown into diftilled wa- 

 ter, and oil of vitriol dropt into it, an effervef- 

 cence enfued, and the black earthy part diffolved, 

 though the reft remained infoluble ; hence the firft 



D 2 part, 



