62 



Dr. John Stenhouse on the 



[Recess, 



brighter as to give the character in question. What strikes one most, 

 however, is the varying relative brightness of the continuous and linear 

 spectra ; sometimes the lines are scarcely seen, and sometimes very little 

 else is seen. This may be nothing more than an illusion ; but in the ab- 

 sence of any certainty that it is so, the impression left on the mind is worth- 

 recording. 



The difficulty of discriminating between the many less prominent lines 

 is immensely increased by the momentary character of the phenomenon. 

 Before the mind has selected an individual, the feeble impression on the 

 retina has vanished ; and before another flash succeeds, the memory of 

 the half-formed choice has vanished with it, and there is nothing on which 

 to found a selection. Otherwise it would be easy enough to measure 

 many more lines. 



III. " Products of the Destructive Distillation of the Sulphobenzolates. 

 —No. II." By John Stenhouse, LL.D., F.R.S., &c. Re- 

 ceived September 8, 1868, 



In a paper published by me in the Proceedings of the Royal Society, 

 1865, I described the manner of preparing sulphobenzolate of sodium and 

 the products of its destructive distillation in a copper retort. These were 

 chiefly sulphide of phenyl and a crystalline substance, of which too small 

 a quantity was obtained to enable me properly to examine it. 



As I wished to procure these products in larger quantities, instead of 

 employing small copper retorts, which were rapidly destroyed, I conducted 

 the operation in tolerably large cast-iron ones heated in a gas-furnace, and 

 found that they were not sensibly corroded even after a great number of 

 distillations. The quantity of sodium-salt decomposed in each distillation 

 was about 200 grammes. 



The oily products obtained by this process, after separation from the 

 supernatant watery layer, were introduced into a copper retort having a 

 bent glass tube luted into the neck and redistilled, the retort being heated 

 to redness towards the close of the operation. In this way a considerable 

 amount of impurity was removed. The bright yellow-coloured oil was 

 then rectified in a glass retort. It began to boil at 80° C, and rose rapidly 

 to 165°C, between which and 180° C. about one-fourth of the liquid came 

 over. The temperature then again rose rapidly to 290° C, and from 290° 

 to 300° a large quantity of nearly pure sulphide of phenyl distilled. The 

 small quantity of dark- coloured residue in the retort was poured into a 

 beaker, where it became semisolid on cooling from the deposition of the 

 crystalline substance I have before mentioned*. 



Phenyl-Mercajptan. 

 The portion boiling between 165° C. and 180° C, on being repeatedly rec- 

 * Proc. Roy. Soc. vol. siv. p. 353. 



