l^S Chemical Inquiries into the Nature of several 



gins to turn soft, however, and the lumps of matter get joined 

 together. 



miction of IVater. 



. 17. It does not undergo any action, from cold water, for it 

 preserves all its physical properties after the maceration of a 

 month in this liquid : nevertheless, if we examine the latter, we 

 fVnd in it a small particle of alkali, and some almost impercepti- 

 ble traces of pearly substance. Hot water has a more decided 

 action on it : thus, when we put into 100 grammes of boiling 

 water one gramme of pearly substance, the latter becomes semi- 

 transparent, it resembles flakes of alumine recently precipitated 

 from a very dilute solution. The water filtered when boiling 

 does not pass over clear ; if before filtering it we allow it to cool, 

 it becomes turbid, and deposits mother of pearl substance : if we 

 then filter it, we find very little potash in it. 1 '5 litre of water 

 (3' 1699 pints English) in which I had boiled 20 grammes of 

 pearly matter, filtered after having been cooled and evaporated, 

 left a residue of subcarbonate and of pearly matter which 

 scarcely weighed 0*1 gr. (ly grain). The matter deposited 

 from the boiling water retains. a little water, which gives it the 

 property of melting at a temperature of 100^ ceutigradcj and a 

 semi -transparency analogous to that of wax. I am strongly in- 

 clined to think that the pearly matter is not dissolved -in hot 

 water, and that it is only divisible in it by combining with 

 water. I formed my opinion upon 1000 parts of water being 

 boiled for two hours over one part of matter, without making it 

 disappear. 



IS. The mother of pearl substance is less soluble ill alcohol 

 than margarine. 100 grammes of this liquid of a gravity of 

 0*834 only dissolved 31 '37 at a temperature of 67*^ centigrade, 

 This solution becomes turbid upon cooling ; and this ought to 

 be the case, since one part . of mother of pearl matter requires 

 318 of alcohol to be dissolved at the temperature of 20-' centir 

 grade: it does not change the colour of hematine ; which 

 proves that the potash is more strongly attracted by the mar- 

 garine than by the colouring principle. 



19. When we mix this solution with water, an abundant pre^- 

 cipitate is fornied : the sediment contains less potash than 

 pearly matter : this is demonstrated by the following experi- 

 ment. I dissolved in boiling alcohol 4-40 gr. of pearly matter 

 containing 4 04 gr. of margarine and 0*36 potash. I poured 

 the liquor while still warm into 1*5 litre of water, and shook the 

 mixture several times. In twelve hours I filtered: the hcjuid eva- 

 porated deposited an inappreciable quantity of pearly" matter : 



it 



