366 CARNEGIE INSTITUTION OF WASHINGTON. 



7. The Effects of Isomorphous Impurities on the Transition Temperatures op 



Crystallized Salts. 



This investigation is a continuation of one carried on last year 

 with Dr. W. B. Meldi'um, who investigated the effects of isomorphous 

 impurities on the transition temperature of sodium chromate. During 

 the present year similar series of experiments were made with the assist- 

 ance of Mr. Victor Yngve, this time upon the transition temperature 

 of various mixtures of pure strontium chloride and bromide, analyzing 

 with care the composition of the mother hquor. The behavior of 

 these salts was found to be different from that of sodium sulphate and 

 chromate. The addition of strontium bromide to the chloride does not 

 raise the transition temperature of strontium chloride, but causes it 

 to diminish. A minimum is reached 6.4° below the transition tempera- 

 ture of the chloride, when the mother liquor contains nearly equal 

 mol-percentages of strontium bromide and chloride. Evidently the 

 phenomenon in question is concerned with the distribution of the 

 impurity between the liquid and solid solutions, and this, of course, 

 varies in every specific case. Incidentally, the temperature of transi- 

 tion from Sr CI2 6H2 to Sr CI2 4H2 was accurately determined for the 

 fii'st time in relation to the international hydrogen scale, and found to 

 be 61.336°, while that of the bromide was'^found to be 88.2°. 



Because a large number of exceptionally able assistants have arranged 

 to work at the laboratory during 1915-16, it is hoped that more extensive 

 series of investigations may be undertaken next winter. 



Sherman, H. C, Columbia University, New York, New York. Continuation 

 of the chemical investigation of the amylases. (For previous reports see 

 Year Books Nos. 11-13. 



During the past year this investigation has been continued in accord- 

 ance mth the plans outlined in previous reports. 



Repeated experiments in the purification of pancreatic and malt 

 amylases have provided material which has been utilized in a more 

 complete comparison of these enzymes with each other and with the 

 malt amylase described by Osborne in 1895 and 1896. Osborne's 

 theory of the chemical nature of the malt enzyme has been shown to be 

 applicable to pancreatic amylase also. By an amplification and exten- 

 sion of this theory, for the discussion of which reference must be made 

 to the more detailed report, it has been possible to offer what appears 

 to be a fairly adequate and entirely consistent explanation of the 

 somewhat complex phenomena observed in studying the purification, 

 activity, and deterioration of both the pancreatic and malt amylases. 

 Two papers dealing with this phase of the work have been pubhshed in 

 the Journal of the American Chemical Society (March and May 1915). 



The experiments to determine the optimum concentrations of different 

 acid substances as activators of malt amylase, referred to in the report 



