TRANSACTIONS OF SECTION B. 579 



another constant for 2HC1 and 2HNO3, while the sulphates and other salts 

 formed possess in the solid state most varied amounts of water of crystallisation, 

 and if this exist.? in solution it would be necessary to assume that the constancy 

 of the neutralisation results is a coincidence, an assumption directly opposed to the 

 probabilities of the case. 



5. On the Magnetic Rotation of Mixtures of Water, and some of the Acids of 

 the Fatty Series 2vith Alcohol and tvith Sul])h%mc Acid, and Observations 

 on Water of Grijstallisation.^ By W. H. Peekin, Ph.D., F.B.8. 



The author first pointed out that the magnetic rotation of water was higher 

 than that of a sum of the value of H.^ + O, as deduced from other compounds, and 

 that therefore the magnetic rotation of a body containing these elements would 

 show whether they existed as water or were otherwise combined. Formic, acetic, 

 and propionic acid were then each mixed with water in the proportions of one mole- 

 cule of acid to one of water, and examined as to their molecular rotation. This was 

 of special interest because acids so diluted were believed to form trihydric alcohols. 

 Alcohol diluted in a similar manner was also examined at the same time for the 

 sake of comparison, because it could not form a compound with water. The result 

 of the niunbers obtained from the magnetic rotation showed that these diluted 

 compounds consist simply of the acids + water, the diluted alcohol giving similar 

 confirmatory numbers. 



Sulphuric acid was then examined in a similar manner, both concentrated and 

 bydrated by the addition of water in the proportion of one, two, and three mole- 

 cules to one of acid. 



From the residts obtained the author concludes that sulphuric acid forms with 

 water the compound (HO)^SO only. 



The study of these hydrated compounds having caused the author to consider 

 the subject of water of crystallisation, he first draws attention to the want of 

 consistency as to the presence or absence of water of crystallisation in the simple 

 salts of metals belonging to the same class, and to the same thing shown in the 

 existence of hydrated methyl-bromide, &c., and concludes that its relation to a 

 salt or other body has not any connection with chemical combination, but that it is 

 purely physical, and is present as a necessity of the crystalline form, and that it is 

 present only when it is conducive to the production of that form which is most 

 readily produced under the circumstances existing at the time, in support of which he 

 brings forward the case of the alums and other isomorphous compounds, and shows 

 that if this be the function of water of crystallisation salts containing it when 

 dissolved wiU no longer remain in union with it, which is now believed to be the 

 case by so many who have studied the subject of the solution of salts. 



6. On the Nature of Liquids. 

 By William Ramsay, Ph.D., and SYDNEr Young, D.Sc. 



The subject of this paper may well be included in a discussion on the nature 

 of solution, for it is impossible to devise a completely satisfactory theory of 

 solution without a knowledge of the molecular structure of the solvent. During 

 the last few years we have made determinations of the vapour pressures, densities 

 of the saturated and unsaturated vapour, specific gravities, and, in some cases, 

 compressibilities of methyl and ethyl alcohol, ether, and acetic acid under various 

 conditions of pressure and temperature. By means of the thermo-dynamical 

 equation 



L = (S.-S,)f.4.. 



the heats of vaporisation have also been calculated. 



The data which bear most strongly on the subject under discussion are the 



' For full paper see Jour. Cltem. Soc, vol. xlix. p. 777. 



p p 2 



