1^4 ESSAYS AND OBSERVATION'S 



vitriol* ; and it is well known that the cauftic 

 fpirit of urine, or of fait ammoniac, does not 

 emit air, when mixed with acids. This con- 

 lideration excited my curiofity, and determin- 

 ed me to inquire into the truth of them all 

 by way of experiment. I therefore engaged 

 myfelf in a fet of trials ; the hiftory of which 

 is here fubjoined. Some new fafts are like- 

 ways occafionally mentioned j and here it 

 will be proper to inform the reader, that I 

 have never mentioned any without fatisfying 

 myfelf of their truth by experiment, tho' I 

 have fometimes taken the liberty to negle<a 

 defcribing the experiments when they feemed 

 fufEciently obvious. 



Desiring to know how much of an acid 

 a calcarious earth will abforb, and what 

 quantity of air is expelled during the dilTolu- 

 tion, I faturated two drams of chalk with 

 diluted fpirit of fait, and ufed the Florentine 

 flafk, as related in a fimilar experiment upon 

 magnefia. Seven drams and one grain of 

 the acid finiflied the difTolution, and the chalk 

 loft two fcruples and eight grains of air. 



This experiment was necefTary before the 

 following, by which I propofed to inquire 



into 



• HofF. Op. T. iv, p. 480. 



