190 Prof. Graham on the Diffusion of Liquids. 



Where two experiments upon the same salt are recorded 

 in the table they are seen to correspond to within 1 part in 

 40, which may be considered as the limit of error in the pre- 

 sent observations. It will be remarked that the diffusion of 

 cane- and starch-sugar is sensibly equal, and double that of 

 gum-arabic. On the other hand, the sugars have less than 

 half the diffusibility of chloride of sodium. It is remarkable 

 that the specifically lightest and densest solutions, those of the 

 sugars and of sulphate of magnesia, approach each other 

 closely in diff'usibility. On comparing together, however, two 

 substances of similar constitution, such as the two salts, chlo- 

 ride of sodium and sulphate of magnesia, that salt appears to 

 be least diffusive of which the solution is densest. 



But the most remarkable result is the diffusion of albumen, 

 which is low out of all proportion when compared with saline 

 bodies. The solution employed was the albumen of the egg, 

 without dilution, but strained through calico and deprived of 

 all vesicular matter. As this liquid, with a density of i'041, 

 Contained only 14--69 parts of dry matter to 100 of water, the 

 proportion diffused is increased in the table to that for 20 

 parts, to correspond with the other substances. In its natural 

 alkaline state the albumen is least diffusive ; but when neutral- 

 ized by acetic acid, a slight precipitation takes place and the 

 liquid filters more easily. The albumen is now sensibly more 

 diffusive than before. Chloride of sodium appears 20 times 

 more diffusible than albumen in the table, but the disparity is 

 really greater ; for nearly one-half of the matter which diffused 

 consisted of inorganic salts. Indeed the experiment appears to 

 promise a delicate method of proximate analysis peculiarly 

 adapted for animal fluids. The value of this low diffusibility 

 in retaining the serous or albuminous fluids within the blood- 

 vessels at once suggests itself. 



Similar results were obtained with egg albumen diluted and 

 well-beaten with 1 and 2 volumes of water. The solution 

 diluted with an equal bulk of water, and made slightly acid 

 with acetic acid, contained 7|- dry matter to 100 water. Dif- 

 fused from two four-ounce bottles of 1*25 inch aperture, for 

 seven days, at a mean temperature of 43°*5 F., it gave pro- 

 ducts of I "73 and 1*48 gi\, from the evaporation of two water- 

 jars, in which cubic crystals of common salt were abundant. 

 The whole matter thus diffused in two cells was found to con- 

 sist of — 



Coagulable albumen . . 0"94 gr. 

 Soluble salts . .... 2'27 grs. 



3*21 grs. 



The diffusion product of the same solution of albumen left 

 alkaline, or without the addition of acetic acid, in the same 



