212 HISTORICAL INTRODUCTION TO CHEMISTRY CHAP. 



"The remainder of the brown mixture was set to digest, 

 in order to see whether the marine 1 acid would saturate 

 itself with manganese. As soon as the mixture became warm, 

 its smell of aqua regis became considerably augmented, and 

 an effervescence also arose, which continued until the 

 following day, when the acid was found to be saturated. On 

 the residue which it had been unable to dissolve, there was 

 again poured one ounce of spirit of salt, whereupon all the 

 above-mentioned phenomena occurred, and the manganese 

 became completely dissolved, except a little siliceous 

 earth." 



" In order clearly to apprehend this novelty I took a 

 retort containing a mixture of manganese and spirit of salt. 

 In front of the neck I bound a bladder emptied of air, and 

 set the retort in hot sand. The bladder became distended 

 by the effervescence in the retort. When the acid no longer 

 effervesced, which was an indication of its saturation, I 

 removed the bladder, and found that this air had coloured 

 it yellow, as if by aqua fortis, but did not contain any trace 

 of fixed air ; it had, however, a quite characteristically 

 suffocating smell, which was most oppressive to the lungs. 

 It resembled the smell of warm aqua regis. The solution 

 in the retort was clear, inclining to yellow, which last-men- 

 tioned colour was caused by its containing iron" (A.C.R. 

 XIII. 5-7). 



The gas which Scheele had thus prepared, he regarded as 

 "marine acid, deprived of phlogiston," and called it " de- 

 phlogisticated marine acid," but when the theory of phlogiston 

 was overthrown, Davy gave to it the name CHLORINE (Greek 

 X^wpos greenish-yellow) on account of its characteristic colour. 

 Although this name was not introduced until 1810, it is used, 

 on account of its simplicity and convenience, throughout 

 the chapter in place of the cumbrous and misleading names 

 given to it during the intervening period. 



The properties of chlorine. In addition to describing 

 its suffocating smell and yellow colour, Scheele states that 



1 Marine acid muriatic acid, the acid derived from brine. 



