146 The Principles of Part lit 



I N this way the matrix of nitre is im- 

 pregnated with the acid of nitre. Let us 

 now fee what this matrix at pfefent con- 

 tains. We have the analyfis of it by 

 Petit in the academy of fciences. He took 

 50!. of old plaifter, and diflblved it in 

 72 Ib. of water. This gave a pungent 

 bitter reddifh liquor, which was in weight 

 to common water as 32 to 31. When 

 the water was boiled into a liquid extract, 

 for it would not harden, it ibon attracted 

 the moifture, and turned liquid again. It 

 turned blue paper red; mewed no effer- 

 vefcence with fp. mtr. or Jp. faL mar. j and 

 when mixed with the former, diflblved 

 leaf gold. OI. vitr. made a violent fer- 

 mentation and precipitation with it. OL 

 tart. p. d. did not eafily mix with it ; but 

 when ftirred, produced a coagulum like 

 butter, and gave a ftrong urinous fmell. 

 Jf fublimate was mixed with the oL farf. 

 no urinous fmell was felt. This coagulum 

 was owing to a feparation and precipita- 

 tion 



