On certain ww PruduHs from mlmd Suhjhuceu tjy 



ift. I iind by the 6th table that 75 grs. filver take 16,54 of marine acid, confequently 

 176,25 grs. fiivcr take up 38,87. 



ad. By the 4th table, I find that loo grs. muriatic acid are fontainedin 257,2 of common 

 fait, confequently 38,87 arc contained in 99,973, that is 100 grs. common fait, then loo grs. 

 of it are neceflary to precipitate the filver. 



XI. 



Experiments on certain Principles obtained frmn Animal Suijlances treated with the Nitrous Aid. 



By C/T. TVelter.* 



JL HE author having treated filk with the nitric acid in order to obtain the oxalic, was 

 furprized to find none, and to obtain at the end of the operation a filky fait of a goldea 

 yellow colour, which adtcd in the fame manner as gunpowder by the coatadl of an ignited 

 coal. As he made this experiment only once, he has thought fit to defcribe it, that others 

 may repeat it. 



He poured upon one part of filk fix parts of common nitrous acid, to which a fmall quan- 

 tity of concentrated nitrous acid was added. After two days' repofe, he diftilled the mixture, 

 and adding the contents of the retort and receiver together, he threw the whole on a 

 filter. The oxalic acid having-cryftallized on the filter, he returned the whole into the re- 

 tort, together \yith a confiderable quantity of water which was ufed in waftiing the filter. A 

 quantity of the water was then diftilled ofi^, but the refidue not cryftallizing, he returned 

 the diftilled liquor ; and after repeating this operation feveral times, he obtained for a refidue 

 an acid liquor of the fame weight as the filk, which contained fmall cryftalline grains. 



This fluid afforded no figns of oxalic acid. It was yellowifh, and tinged the fingers and 

 filk of the fame colour, which was not weakened by waihing with water. 



Cit. Welter faturated this fluid with lime -, and after having concentrated it, he poured 

 alcohol ,to it, which feparated a fubftance of a gummy appearance. The alcohol diluted with 

 water was then evaporated, -and left a yellow fubftance mixed with the folutions of calcareous 

 nitrate and muriate. He decompofed thefe lalts by the carbonate of potafh, and the fluid fe» 

 parated from the carbornte of lime was fubmitted to evaporation. It afforded gold-coloured 

 cryftals as fine as filk, which detonated like gunpowder with a black fmoke. Thefe cryftals 

 are foluble in vrater and in alcohol, and cryftallize by cooling. The oxygenated muriatic 

 acid renders them colourlefs. The fulphuric acid difengages a fmell of nitric acid. The 

 muriatic acid occafions in thefe folutions a precipitate of fmall whitilh micaceous cryftals, 

 which are volatile, and in the fire emit a bitter and inflammable fume. 



• Abridged account of a memoir rer.d before the French National Inftitutc. Bulletin de la Sociele Philo- 

 matique, no. 45. Germinal vii. 



-Vol. III.— September 1799. O ' This 



b 



