VOL. XXXIII.] PHILOSOPHICAL TRANSACTIONS. Q 



gave occasion to the following experiments on metallic bodies, in order to ob- 

 serve if the same change of colour could be produced in any of them. 



To a solution of silver in aquafortis was poured the lixivium of blood, which 

 occasioned a coaguiutn of a pure flesh colour. The lixivium made with flesh 

 produced a whitish coagulum, and the ol. tartari a much whiter. By the addi- 

 tion of the sp. salis to each of these, the bloom of the flesh colour was taken 

 off" in the first, but sufl^ered no other change. In the id the coagulum was a 

 little tinged with blue ; and in the 3d the white was manifestly improved. The 

 bluish tinge in the 2d of these experiments cannot entirely be assigned as the 

 effect of the lixivium with flesh, because silver, when thus dissolved, whether 

 precipitated with salt-water, or ol. tartari, will, after it has stood some time, 

 contract a bluish tinge, and this from an alloy of copper, from which it is not 

 entirely freed. 



The same liquors were used to precipitate the mercury In the mere, sublim. 

 corr. dissolved in water ; the consequence of which was, that the lixivium with 

 blood produced a pure yellow ; the lixivium with flesh an orange colour; and 

 the ol. tartari a dingy red. The addition of the sp. salis to these, made some 

 very odd alterations ; for the first changed its yellow colour for an orange ; the 

 2d its orange for a blue; and the 3d became quite clear again without any 

 colour. The blue colour in the mixture of the lixivium with flesh, and solution 

 of sublimate, may be accounted for from the vitriol in the composition of the sub- 

 limate ; but it will not be so easy to give a reason why the same colour should 

 not have been produced from the lixivium with blood, and the same solution. 



Copper, when dissolved in aquafortis, tinges the water of a green colour ; 

 and if to this you pour the two lixivia of blood and flesh, the coagula are much 

 alike, viz. a white tinged with green; but when you add the sp. salis, they both 

 change, and become of a colour not unlike the copper itself before it is dissolved 

 in the aquafortis. If the ol. tartari be poured to a solution of the copper, the 

 coagulum is a pale green, which coagulum the sp. salis dissolves, and leaves the 

 liquor clear, but green, as before precipitation. 



Tin-glass,* an imperfect metal, dissolved in aquafortis, and mixed with the 

 lixivium of blood, made a milky coagulum ; and by the addition of the sp. 

 salis, after some time standing, its upper surface changed to a light blue. The 

 lixivium of flesh and the ol. tartari produced both white coagula, which the sp. 

 salis scarcely alters. 



Lead, dissolved in spirit of vinegar, produces much the same white coagulum, 

 when mixed either with the lixivium of blood, flesh, or the ol. tartari, nor 

 does the sp. salis make any alteration. 



* Bismuth. 

 VOL. VII. C 



