M. Serullas, on Hydriodide of Carbon. 297 



Leslie's, constructed on the other plan. — Ann. de Chimie et de 

 Physique, xxi. 82. 



2. Memoir on the Density of Vapours, by M. Ces. Despretz, 



Although we can find no new facts in this paper, it deserves 

 notice from the mode of investigation. The process followed 

 for comparing the weights of gases, has never been applied to 

 vapours, because it was foreseen, that, on taking the densities 

 at the boiling points of the liquids, the contact of the cool sides 

 of the balloon would cause a portion of vapour to be liquefied. 

 It would not be so, if the experiments were made at the tempera- 

 ture of the surrounding bodies. We might then weigh vapours 

 as we weigh gases. M. Despretz conceives himself to be the 

 first person who has done this. We obtain, adds he, vapour 

 perfectly pure, and at the actual temperature of the surrounding 

 bodies, by fixing a stop-cock to a barometric tube, whose in- 

 ternal diameter is triple that of the ordinary tubes, and by 

 introducing into this tube the liquid whose vapour we wish to 

 weigh. We adapt a balloon to it, well exhausted of air ; this 

 is soon filled with vapour ; an ordinary barometer is plunged 

 into the same bath, so that we know the elastic force of the 

 vapour weighed, by the difference of height of the mercury in 

 the two tubes. Lastly, we judge if the elastic force is at the 

 maximum, and consequently, if the space be saturated, by the 

 inspection of a third barometer-tube. In this third tube, there 

 is liquid in excess, which will not be the case with the tube 

 which furnishes vapour to the balloon, except in so far as the 

 mercury in it is at the same height as in the first. 



We consider the suggestion of M. Despretz ingenious, but 

 the details are obscure. A plate of his apparatus should have 

 been given in the Annales. — Ann. de Ch. et de Ph. xxi. 143. 



3. On the Hydriodide of Carbon (hydriodure ;) a new Mode of 

 obtaining it. By M. Serullas. 



The preparation of the hydriodide of carbon, by the action 

 of potassium on alcohol holding iodine in solution, being prac- 

 ticable by few persons, from the price of potassium, M. Serullas 

 sought to obtain this new body by other and easier means. 

 After different attempts, all founded on the re-action of bodies 

 which could present nascent defiant gas to iodine, M. S. 

 has succeeded in readily procuring hydriodide of carbon. On 

 chloride of iodine, made by saturating pulverulent iodine with 

 chlorine in a globe, he poured from five to six times its weight 

 of alcohol, at 34°, (about 0.847 sp. gr.) The liquid, at first 

 turbid, became clear in a few instants with deposition of some 

 saline matters proceeding from the impurity of the iodine, as 

 also of a small quantity of an acid iodate having potash for its 

 base, which likewise existed in the iodine. 



This alcoholic solution of chloride of iodine being treated 



