Reflexions on Cob alt ^ <&c. 36$ 



arfenic makes it give a blue tinge to glafs, 

 it is becaufe it contains a portion of cobalt, 

 which is not eafily dephlogifticated, but re- 

 mains in a reguline ftate, and while it remains 

 in this ftate, it can give no colour to glafs, 

 but the addition of arfenic dephlogifticates 

 this portion of cobalt, and thus enables it to 

 unite to, and tinge glafs, and this is fo true, 

 that the addition of nitre, which dephlogif- 

 ticates ftill more powerfully than arfenic, 

 produces the fame effed, as Mr. Bergman has 

 {hewn in his elaborate differtation on Nickel, 

 2 Nov. Al. Ups. p. 243. fo chat arfenic is 

 no way neceflary ; and moreover it is abfo- 

 lutely falfe, that the addition of iron and 

 arfenic will ever give nickel the properties 

 of cobalt, as Mr. Monnet himfelf muft well 

 know. However, the reafons he alledges to 

 prove the identity of thefe femi- metals are, 



6. i' That cobalt and nickel are foluble 

 in the fame acids, and ated on by thefe acids 

 in the fame manner, all the difference being 

 that the folutions of cobalt are red, and thofe 

 of nickel green ; a difference affuredly ve~y 

 great, and which no addition of iron and arfe* 

 nic to nickel will alter, as it fhould according 

 to his fyftem ; for let him combine iron and 

 arfenic with nickel as he pleafes, he will never 

 make a fubftance whofe folution in acids will 

 be red, as that of cobalt is; But further, if 



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