152 SCIENCE PROGRESS. 



dissolves slowly in the cold, but rapidly on heating. The 

 solution obtained should be evaporated in vacuo at a low 

 temperature. The resulting solid is a transparent jelly 

 which dries into translucent, yellowish plates, which in 

 their physical properties resemble dried serum-albumin. 



(B) This colloid is similarly prepared, except that the 

 temperature in the sealed tubes is allowed to rise to 



135° C. 



(C) Colloide aspartique is prepared by the action of a 

 current of gaseous ammonia heated to 170° C, on solid 

 aspartic anhydride. The product is washed with water, 

 and after evaporation in vacuo yields a substance similar 

 in appearance to the colloid (A). 



It will be seen from this that the obtaining of albumin 

 by these methods was hardly to be expected, but rather one 

 would get a product which would be, as it were, a skeleton 

 of a proteid ; in all cases heavy molecules were formed ; in 

 all cases the result was a colloid substance exhibiting:", as we 

 shall see directly, many of the properties hitherto deemed 

 diagnostic of proteids, and in the case of the two first 

 colloids there was present not only the amidogen, but also 

 the aromatic radicle. 



The resemblance between the proteids and these syn- 

 thesised colloids is, however, remarkably close, and Dr. 

 J. W. Pickering, who has been instrumental in bringing 

 Grimaux's work prominently before English physiologists, 

 has confirmed most of his results, and also discovered cer- 

 tain other similarities which were not noted by Grimaux. 

 I take the following; brief resume of the chief of these 

 similarities from Pickering's papers (3). 



1. All give the xanthoproteic reaction. 



2. With copper sulphate and caustic potash, A gives a 

 blue violet ; B, nil ; C, a typical violet coloration. 



3. Their solutions do not coagulate on heating in the 

 absence of salt ; if, however, a trace of a soluble barium, 

 strontium, or calcium salt is present, opalescence occurs at 

 56 and coagulation at 75° C. 



4. The colloids are removed from solution (rising to the 

 surface of the fluid) by saturation with magnesium sulphate, 



