4 A N A LYSIS of 



the water, or any other fubftance with which it is then 

 in contacft ; io that a better opportunity is given to the 

 phlogifton emitted from the bones to unite with that 

 air in a different manner, and form phlogifticated air, 

 which is therefore after the procefs found in a greater 

 proportion than in the other cafes, to which alone a due 

 attention has hitherto been given. When thefe bones 

 are heated over lime water, there is a copious precipita- 

 tion of the lime. Here 1 would obferve that the phlo- 

 gifton neceffary to form this fixed air could only come 

 from the bones in becoming white, as they had been cal- 

 cined in as great a degree of heat as 1 could produce, fo 

 that no kind of air could have been expelled from them 

 while excluded from accefs of air. 



Having by means of a burning lens heated 140.5 

 grains of well burned black bones in 23.75 ounce mea- 

 fures of air, it was reduced to 20 ounce meafures, com- 

 pletely phlogifticated, without any mixture of fixed or 

 inflammable air in it. According to this experiment, 

 the quantity of pure air in 1 00 ounce meafures of at- 

 mofpherical air was only 15.78 parts inftead of 27. 



Heating 267 grains of thefe bones in 30 ounce mea- 

 fures of air, it was reduced to 25.5 ounce meafures com- 

 pletely phlogifticated, which was in the proportion of 

 1 5 parts of dephlogifticated air in 1 00 of atmofpherical. 

 In thefe experiments with bones there is fometimes a 

 fmall lofs of weight, owing, I doubt not, to fomething 

 befides phlogifton being expelled from them by the in- 

 tenfc heat of the lens ; and during the procefs I could per- 

 ceive a flight vapour rifing from them. When I ma- 

 naged the heat fo that it was not more than neceflary to 

 whiten the bones, they neither gained nor loft any 

 weight ; at leaft the lofs was very inconfiderable. 



I had flmilar refults from experiments made with fmall 

 y)o\i{hed Jleel needles. For when they were heated fo as 



only 



