20C Ludehing and Star)' — Specific Heat of Ammonia. 



for a time, episodes of glaciation that are not widely sep- 

 arated from their neighboring episodes. But this will be 

 wholesome for the time, just as species-making was. It is, in 

 deed, almost necessary to the ultimate end sought to make 

 the sharpest possible discriminations, even if they result in 

 excessive divisions which shall last only until such time as they 

 may be brought together by interstitial formations. 



Although not fully placed before the public, at least four 

 divisions of the drift south of the Great Lakes are now being 

 employed as working hypotheses and are gaining strength 

 under the tests of the field. The interval I have chiefly dis- 

 cussed in this paper is the middle one. I have regarded it as 

 the most important one, possibly the only one that will ulti- 

 mately stand as possessing an epochal value, but I am in sym- 

 pathy with the movement led by Dr. Geikie, because it will 

 develop a more precise delineation of the history of glaciation. 

 If the terminal moraines of Ontario have much divisional im- 

 portance, they will make the present working classification of 

 of this country closely analogous to that advanced by the dis- 

 tinguished Scotch glacialist. 



It is the present judgment of the majority of critical work- 

 ers in both the American and European field, that aihid all 

 future tests two or more of these divisions at least will stand 

 as well sanctioned epochs, to whatever grade others may be 

 relegated by the fuller knowledge of the future. 



Art. XXIV. — The Specific Heat of Liquid Ammonia; by 

 C. LuDEKiisfG- and J. E. Starr. 



The specific heat of liquid ammonia, though it has often 

 been the subject of calculation in development of theory 

 and practice, has not yet been satisfactorily determined experi- 

 mentally, if we except the work of Regnault. His results, 

 however, were unfortunately lost during the Paris Commune. 

 He assumed the specific heat to be 0799. Since then the 

 interest in this constant has very, considerably increased 

 through the rapid development of the artificial ice industry. 

 Generally the specific heat has been taken at unity. Thus 

 DeVolson Wood in his " Thermodynamics," page 337, recom- 

 mends this value " until the experimental value is determined." 



It was our good fortune to have ready access to all the 

 means necessary for executing the somewhat laborious experi- 

 ments involved and we take this opportunity to present briefly 



