28 HISTORICAL INTRODUCTION TO CHEMISTRY CHAP. 



by the careful experiments of Robert Boyle on the calcina- 

 tion of copper and iron, as well as of tin and lead. Boyle's 

 observations showed a gain of : 



30 to 49 grains on 480 grains of copper x 

 60 480 tin 



66 240 iron 



7 480 ,, lead (in spite of loss) 



whilst silver showed a gain of only 2 grains on 212. 

 Boyle's experiments were carried out as follows : 



" Into a very shallow crucible, we put an ounce of copper- 

 plates, and set it in a cupelling furnace, where it was kept 

 for two hours and then being taken out, we weighed the 

 copper, which had not been melted (having first blown off 

 all the ashes), and found it had gained thirty grains." 



A similar experiment with an ounce of copper filings 

 gave an increase of 49 grains. 



" Upon a good cupel, we put an ounce of English tin, of 

 the better sort ; and having placed it in the furnace, under 

 a muffler, though it presently melted, yet it did not forsake its 

 place, but remain upon the concave surface of the cupel, 

 till, at the end of about two hours, it appeared to have been 

 well-calcined ; and then being taken out, and weighed by 

 itself, the ounce of metal was found to have gained no less 

 than one dram." 



" An ounce of lead was put upon a cupel, made of calcined 

 hartshorn, and placed under a muffler, after the cupel was 

 first made hot, and then weighed. This lead did not enter 

 the cupel, but was turned into a kind of litharge on the top of 

 it, and broke the cupel, whereby some part of the latter was 

 lost in the furnace ; yet the rest, together with the litharge, 

 weighed seven grains more than the lead and heated cupel, 

 when they were put in." 



" Four drams of the filings of steel, being kept two hours 



1 20 grains = I scruple 

 3 scruples = I dram 

 8 drams = I ounce. 



