J3I6 



were sloj)pe(l the sooner us tlie (iiiestion of what is llie oiigiiial 

 product of change is not of much iinporfance in these experiments. 

 The change of carbamate lo carbonate is generally quicker than the 

 enzyme action and the carbonic acid converts all carbamate as well 

 as carbonate into bicarbonate. 



The powdered ammonium carbonate had practically the composi- 

 tion NHjHCOj. A solution of ammonium carbonate (= 2 '/o I'l'ea) 

 will therefore mean in this paper a concentration of about 2 > 2,63 '/o 

 ammonium carbonate. 



The required amount of Soja-meal was digested at 27° with a 

 solution of ainmonium carbonate, thi-ough which a stream of carbo- 

 nic acid was maintained dnring about one hour. After mixing with 

 some kiezelgur a clear filtrate was very easily obtained, only slightly 

 opalescent, if large (piantities of Soja-meal had been used. 



It is obvious, that the electrometric estimation of pn is impossible 

 in a solution of ammonium carbonate, which is to be ke])t saturated 

 with carbonic acid. The much less accurate colorimetric method 

 had therefore to be applied here. By using Tropaeolin 00 in order 

 to give the Sörknsen phosphate solutions as nearly as possible the same 

 colour as the ammonium carbonate extract of Soja-meal and kiezel- 

 gur and with rosolic acid as indicator, the pu of an ammonium 

 carbonate solution (=^2* „ urea) with J ,8fi g. of Soja pei- JOO c.c, 

 through which carbonic acid had been passed at 27°, could be 

 estimated to be about 7,0. By adding ammonium carbonate (= 0,5 " „ 

 nrea) and passing carbonic acid again no distinct shifting of the /;// 

 was observed. 



As will be seen, no great accuracy is required in these experi- 

 ments, where — is so much larger than above in the phos- 



nc ; 



0,4341 

 phate mixtures, that the curves all approach to straight lines. 



As types of the numerous experiments only the following will 

 be recorded here. 



In a i'ound bottomed flask of ^ Litre, placed in a waterbath of 

 27°, 15,125 g. of ammonium carbonate, dissolved to 250 c.c, and 

 6 g. of Soja-meal were introduced. A few drops of octylalcohol 

 were added to prevent foaming. 



The carbonic acid from a steel cylinder was first passed through 

 a narrow copper tube of about J 50 cm. length, placed in the bath 

 and then through two wash-bottles, filled with water, also in the 

 bath of 27°. The stream of carbonic acid, in this way brought to 

 the required temperature and saturated with watervapour, was passed 



