278 



PROCEEDINGS OP THE AMERICAN ACADEMY. 



the same material over and over again, and it introduces a complication 

 which might seriously retard the speed of attaining equilibrium, and 

 hence the constancy of the desired point. 



After studying with care the published records of all the field of inor- 

 ganic chemistry, about two dozen salts were selected as probably suitable 

 lor the work in hand. Of these magnesic and nickelous sulphates, calcic 

 and nickelous nitrates, nickelous chloride and borax were rejected as 

 being too inconstant in their indications. The lack of constancy was due 

 sometimes to the smallness of the latent heat of transition, and sometimes 

 to a superabundance of crystalline hydrates. On the other hand, at least 

 eight of the new salts gave results comparable in certainty with those 

 given by the ever trustworthy Glauber's salt. These salts are given in 

 the table below. 



TRANSITION TEMPERATURES OF NINE SALTS. 



The temperatures given above are only approximations, and are sul)- 

 ject to future revision ; at this stage of the work our effort has been only 

 to determine if the points were constant, and not to fix their absolute 

 value. Besides these nine, several other salts promise well. Baric 

 hydrate, given above, was our first trial of three components, for the car- 

 bonate was naturally allowed to be present. The study of such quintuple 

 points has now been interrupted by Messrs. Meyerhoffer and Saunders's 

 claim. 



