1884.] The Influence of Stress and Strain on Matter. 107 



the air, and is so soluble that a vast amount of it is required to 

 saturate even a small quantity of serum. 



Various other salts have been examined. Many that are not very 

 soluble produce no effect at all ; among these may be mentioned 

 potassium nitrate, potassium sulphate, potassium chloride, potassium 

 chlorate, ammonium chloride. ' 



Others, like sodium chloride and sodium nitrate, precipitate 

 globulin completely, but slowly, in simple serum. Sodium nitrate 

 precipitates serum-albumin completely, but slowly, after saturation 

 with magnesium sulphate. 



Sodium nitrate has a very marked effect in lowering the heat- 

 coagulation of a proteid. Potassium nitrate acts similarly, but not 

 nearly to so great an extent as sodium nitrate. 



Fuller particulars concerning these various salts will be given 

 when the experiments relating to them are completed. 



The most important results that these researches show are as 

 follows : 



(1.) That the albumin of serum can by the process of fractional 

 heat-coagulation be shown to consist of three separate proteids, which 

 may be called provisionally serum-albumin numbers 1, 2, and 3 (to 

 avoid a multiplicity of terms). In certain animals only two of these 

 are present. 



(2.) That the precipitates described by Fredericq as occurring in 

 serum at temperatures below 70 C. have, in this series of experi- 

 ments, in which some hundreds of heat- coagulation determinations 

 have been made, been found never to occur. 



(3.) That the albumins of serum can be completely precipitated 

 after saturation with magnesium sulphate and removal of the serum- 

 globulin by saturation with sodium sulphate. 



(4.) That potassium acetate, added in excess to solution of a 

 proteid, e.g., serum or solution of egg-albumin, completely precipitates 

 the proteid therefrom without coagulating it. 



IV. ' The Influence of Stress and Strain on the Physical 

 Properties of Matter."* Part I. Moduli of Elasticity 

 continued. Relations between Moduli of Elasticity, Thermal 

 Capacity, and other Physical Constants. By HERBERT 

 TOMLINSON, B.A. Communicated by Professor W. GRYLLS 

 ADAMS, M.A., F.R.S. Received May 28, 1884. 



(Abstract.) 

 The thermal capacity of each of the wires already used for the 



* The original title of the paper has been altered to the above, as being more 

 expct in expression. 



