88 Colloidal Nitrogen in Urinc from a Dog [Sept. 



The writers lately embraced an opportunity to study the colloidal 

 nitrogen Output in the urine of a dog with a large tumor. 



The dog upon which this study was made had a hard calcified 

 growth about the size of an orange in one of the breasts. The 

 tumor involved the nipple and the breast tissue for some distance 

 around the nipple. Several metastatic deposits were present along 

 the "breast lines." Microscopic examination of sections of the 

 original growth and of the metastatic infiltrations, according to 

 several pathologists who examined them, indicated that the tumor 

 was a chondroma which had undergone carcinomatous degenera- 

 tion. Other pathologists, on the contrary, believed the growth to 

 be of a benign nature, with the histological structure of a chon- 

 droma. 



For the determination of colloidal nitrogen the alcoholic pre- 

 cipitation method of Salkowski was used, with modifications, as 

 follows :^ 



The total nitrogen was determlned in 5 c.c. of the urine by the 

 Kjeldahl process. Two portions of 100 c.c. each of the urine were 

 evaporated in a porcelain dish over a gently steaming water bath tili 

 they were of the consistency of thin syrup. The residues were then 

 taken up in 100 c.c. of alcohol (98.5 per cent.) and thoroughly 

 stirred. The alcoholic extracts were then filtered through ashless 

 filter papers, and the precipitates washed with alcohol. 



We determined the effect of dialysis upon this alcohol-precip- 

 itable, so-called "colloidal," nitrogenous material. Most colloidal 

 substances fail to dialyze through the very best grade of parchment 

 paper. Only that fraction of the alcoholic precipitate which would 

 remain indiffusible under suitable conditions of dialysis could be 

 called "colloidal," at the present stage of our knowledge of the 

 subject. Accordingly, the two precipitates on the ashless filter 

 paper were treated as follows : 



The precipitate on one filter paper, together with the filter, was 

 placed in a Kjeldahl flask, digested with sulfuric acid, and the 

 nitrogen determined in the usual way. The second precipitate and 



*Before subjection to analysis the urine was first tested for protein, which, 

 if found, was removed by means of heat coagulation aided by the addition of a 

 few drops of dilute acetic acid Solution. 



