308 Progress of Foreign Science. 



purity, by decomposing a very concentrated alcoholic solution 

 of hydroxaiithate of potasli, with an alcoholic solution of 

 chloride of calcium. He thinks it probable that the greater 

 part of the precipitates, produced by decomposing the me- 

 tallic salts with hydroxanthate of potash, are combinations 

 of xanthogen with the metal of the salt employed. The 

 precipitate from copper is not attacked either by sulphuric 

 or muriatic acid, whether concentrated or dilute ; nitric acid, 

 however, (specific gravity 1.32,) dissolves it easily, with a pro- 

 duction of gas, and a substance which has the aspect of fat, 

 at first coloured greenish-yellow, then whitish-yellow. The 

 xanthide of lead is prepared with nitrate of lead and hydroxan- 

 thate of potash ; it is white, and falls down in flocks. Xanthic 

 oil is given out on exposing these two xanthides to heat in a 

 retort. 



Hydroxanihic acid is liquid at common temperatures, and 

 even under them ; it has completely the appearance of a trans- 

 parent colourless oil. Its specific gravity is greater than that 

 of water. It does not combine with this liquid. On contact of 

 air it is soon covered with a white opaque crust. When much 

 divided among water, it is completely destroyed in a short time. 

 Its smell is strong and peculiar. It has at first an acid taste, 

 then a very strongly astringent and bitter one. It reddens 

 powerfully litmus paper, but a portion of the red is not long in 

 becoming yellowish-white. To obtain hydroxanthic acid we 

 introduce the hydroxanthate of potash into a long and nar- 

 row glass ; we pour into it sulphuric acid, diluted with four or 

 five volumes of water, aiding the re-action by a gentle agita- 

 tion ; two or three minutes afterwards, we add to the milky 

 mixture, at intervals of some seconds, from three to four 

 volumes of water, so managing it that the new acid may collect 

 into a single mass at the bottom of the vessel ; then we add 

 speedily fifty or sixty volumes of water. It remains now only 

 to withdraw the water, and to pour on new portions as speedily 

 as possible ; to withdraw this, and so in succession, till the 

 washings no longer aff^ect a solution of barytes. Instead of 

 sulphuric acid, we may equally make use of the muriatic. 



Hydroxanthic acid dissolves very readily in a watery solution 

 of potash, barytes, or ammonia ; it expels carbonic acid from 

 the carbonate of potash, giving birth to a salt vvhicli entirely 

 yesembles that obtained by neutralizing an alcoholic solution of 

 potash with carburet of sulphur. With carbonate of ammonia 

 it furnishes hydroxanthate of ammonia, with disengagement 

 of carbonic acid. It decomposes, also, carbonate of barytes, 

 forming hydroxanthate of barytes, which is very soluble in 

 •water and alcohol. The re-action is, in general, much more 

 lively when the salifiable bases or their carbonates are intro- 

 duced in the solid state, into hydroxanthic acid, covered 



