428 C. E. Linebarger — Molecular Masses of Dextrine, etc. 



seems to point to a more or less distant analogy with the 

 periodic system of the elements, where likewise the number 

 seven plays an important part. It will be interesting to see if 

 subsequent determinations of the osmotic pressures of colloids 

 will show this to be general. I am at present engaged in test- 

 ing an apparatus for the rapid and accurate determination of 

 the osmotic pressures of such substances as do not diatyze 

 through parchment paper, etc., which will enable me to get at 

 the molecular masses of the substances. These determinations 

 will be carried out mostly with those substances treated of in 

 Physiological Chemistry. When once the molecular masses of 

 the complex colloid substances of animal and vegetable origin 

 are known, a great stride in advance will have been made. 

 As the value of an investigation of this kind depends upon 

 the variety and number of substances examined, I take this 

 opportunity to request those, who may have albuminoids or 

 proteids of any kind, to kindly furnish me with a sample, in 

 order that I may determine its osmotic pressure, and hence 

 molecular mass. But a small quantity is necessary, two or 

 three grams sufficing. 



The results of Pfeffer's measurements fully confirm the 

 observations made in my first paper on the nature of colloid 

 solutions. Since its publication there has come to my notice 

 an article by A. Sabanejew,"* who has determined the lower- 

 ing of the freezing point of solutions of egg albumin. The 

 depression is indeed slight — in the hundredths of degrees, — 

 but quite perceptible and sufficient to enable him to deduce 

 the molecular mass of the albumin — 14000. This proves that 

 solutions of colloids as well as of crystalloids have a lower 

 point of solidification than the solvent alone, and hence that 

 the difference, if it exists, is only one of degree. 



Recently, too, in an article on " Solution and Pseudosolu- 

 tion "f it is stated as one of the theoretical results of quite a series 

 of experiments on the behavior of various colloid solutions that 

 " there is a continuous series of grades of solution passing 

 without break from suspension to crystallizable solution." The 

 continuation of this work, which is promised, will probably 

 throw much light upon the subject. 



Chicago, 111., 240 La Salle avenue. 



*Jour. Russ. Soc, ii, 7 (1891). 



f Jour. Chem. Soc., cccli", 171 (1892). 



