1905.] On certain Properties of Solutions of Chloroform, etc. 93 



Separation or Coagulation of the Lipoid Emulsions by Chloroform and other 



Substances. 



An interesting physical effect is seen as the amount of chloroform added to 

 the emulsion of lipoids in saline is increased. At a certain stage, dependent 

 upon the richness of the emulsion in lipoid, a complete separation of the 

 lipoid, in a butter-like mass, is obtained, leaving the saline practically free 

 from lipoid. The phenomenon suggests a resemblance to the similar precipi- 

 tation of proteid observed under like conditions, but there is this difference, 

 that in the case of proteid, when the amount of anaesthetic is sufficient, the 

 precipitate is permanently altered, being coagulated and rendered insoluble in 

 water or saline, while the lipoid is only physically thrown out, and can be 

 re-dissolved in ether and again made into an emulsion with saline. This 

 phenomenon of physical aggregation of the lipoid by the anaesthetic is the 

 more remarkable because the emulsions are exceedingly permanent and 

 remain unaltered for days. The permanency is probably due to lecithin, and 

 the emulsion under the microscope shows small bodies, which are not in 

 most cases spheres, but show the appearance of bi-concave discs of varying 

 size, many being no larger than mammalian blood-corpuscles. The physical 

 cause for the production of such discs is at present unknown to us, but the 

 matter is being further investigated. 



In the case of the emulsion of brain tissue (containing 4*07 per cent, of 

 lipoid) coagulation or separation of the emulsion occurs in the cold when 

 about 2 per cent, of chloroform has been added, and the coagulation occurs 

 much earlier at body temperature. The coagulum or separated lipoid forms 

 a jelly-like mass, which later separates into a thin whitish fluid and a butter- 

 like mass. These emulsions can also be coagulated or separated by solutions 

 of neutral salts, alcohol, benzol, xylol, and other organic fluids. 



The precipitation may be due to a lowering of surface tension in the 

 emulsion, and presents an interesting analogy with the precipitation of 

 proteids and other colloids from solution by neutral salts, chloroform, and 

 other organic substances which act as anaesthetics. It may be noted in this 

 connection that froth on serum disappears when chloroform is dropped into it, 

 and we have noticed the absence of frothing on stirring on the chloroform 

 side of our densimeter as compared with the control side. 



Experiment 4. — Ethereal Extract of Serum. 



The extract was obtained as described, the percentage of ethereal extractive 

 (lipoid) in the emulsion in saline as introduced into the densimeter was 0*206. 

 The results are given in Table IV, and shown graphically in Curve 2, fig. 3, 

 where they are contrasted with the results given by entire serum. 



