Miscellaneous Papers. SOS 



jority of cases involving practical laboratory work, the actions theo- 

 retically indicated did not occur. 



As long ago as the early eighties it was known to students, as a 

 sort of marvel, that insoluble chromic chloride, when brought into 

 the presence of a billionth part of the soluble chromic chloride, in 

 water, became transformed in its nature, thus becoming soluble, 

 like the latter salt. In those days we found that tin brought into 

 contact with cold hydrochloric acid alone would yield us nothing. 

 But we soon learned the trick of the master, and so, by the addi- 

 tion of a very small portion of platinum solution, presently had the 

 metal dissolved. At a later date we were, in the quantitative lab- 

 oratory, let into the secret of Fresenius, namely, that ever so small 

 a portion of potassium permanganate would work the same miracle 

 with almost all insoluble and "fractious" compounds. 



In these determinations the strange thing of it all was this: the 

 catalyzing substance ivould remain, in every case, unaffected. It 

 could be used over and over again. Once initiated into the mys- 

 teries of the organic laboratory, we found that inorganic salts are 

 not by any means the only catalytic substances. Microbes and 

 bacteria we found to be the cause of all kinds of fermentations: 

 the "yeast plant" causing sugar to change into alcohol; the "vine- 

 gar plant transforming alcohol into acetic acid; the "lactic ferment" 

 changing sugar into lactic acid; "nitrous and nitric ferments" 

 changing am moniacal products into the nitrates of the soil. In all 

 these cases the protoplasm of the organism had, in the presence of 

 these compounds, wrought transfer without any change of the or- 

 ganic material. Diastase from barley malt, ptyalin from saliva, 

 araplopepsin from pancreatic juice — all these we soon discovered 

 to have the power of changing starch into sugar. Pepsin mingled 

 with gastric juice would change insoluble albuminous forms into 

 soluble forms, while rennet in digesto would work the miracle on 

 400,000 times its weight in the casein of milk. 



Hardly had we become accustomed to thinking in terms of these 

 last-named "enzymes" when we were introduced to the "colloidal 

 suspensions." These, like the suspensions above noted as "solu- 

 tions," required a membrane to separate the two elements. Incited 

 by the wonder of these reactions, we set to work to make, for in- 

 stance, the interesting platinum suspension, which is brown, in 

 color. We then wrought out the ruby-colored suspension, of gold; 

 the yellow one, of silver — performing these reactions at an electric 

 plant where a high potential could be furnished. All these sus- 

 pensions we found, when invited to determine them by means of 



