86 THE JOURNAL OF PHARMACOLOGY. 



other observers maintain that the true active principle is a small quantity 

 ofabody derived from the seeds and held in solution in the oil. The question 

 possesses considerable practical interest, because, if the former view he cor- 

 rect, we cannot liope to diminish the necessary dose: whereas, if the latter 

 view be the correct one, and wei were able to obtain the active principle in 

 i state of purity, a very small dose of a probably tasteless substance would 

 suffice t<> produce purgation. In 1890 Meyer strove to show (Arch, fur 

 Exper. Path. un<l Pharmakol., Leipsiz, bd. xxviii.) that ricinoleic acid and 

 its salts were as active as castor oil, but there is always a suspicion that his 

 preparations contained a small amount of the hypothetical active principle, 

 and that their activity was duv to this, lie has again returned to the sub- 

 ject (Arch, fur Exper. Path, und Pharmakol., Leipsiz, 1897, bd. xxxviii.). 

 and, after showing that castor oil does not lose its activity by being heated 

 to 300° C, or by treatment with dry hydrochloric acid, by boiling with 

 caustic potash, or by other methods calculated to destroy any known ac- 

 tive principle, he comes to the conclusion that ricinoleic acid is the only 

 active substance present in the oil, and that it develops its specific action 

 in the intestine by being saponified, and thereby rendered soluble. Ricino- 

 leic acid has, however, no specially irritating properties, and it is difficult 

 to explain its action as a. purgative. 



The Nitric Acid Test in the Examination of the Urine. — In con- 

 formity with the instructions usually given in text-books on urinary analysis, 

 the nitric acid test for albumin is generally employed in the following 

 manner: A certain amount of urine is placed in a test-tube, and nitric acid 

 allowed to trickle down the sides of the tube, so as to form a distinct layer 

 beneath the mine. In the presence of albumin a cloudy ring will be seen 

 to form at the zone of contact of the two fluids. If it is only desired to tesl 

 a given urine for albumin, no objection can be made to this procedure. 

 'The amount of general information, however, which can thus be obtained 

 is rather limited, and a great deal more can be learned from a specimen 

 if a conical glass of about two-ounce capacity be used in place of the test- 

 tube. This modification is quite generally accepted in the hospitals of 

 France, and many of Germany, and undoubtedly deserves the attention of 

 American physicians. 



The glass is tilled to about one-half of its capacity with the urine to be 

 examined, when nitric acid is carefully added from the side, or through 

 a pipette carried to the bottom of the vessel, so as to form a layer of about 

 one-hall to three-quarters of an inch in depth beneath the urine. 



Under normal conditions a brick-red to a rose-colored band, referable 

 to the presence of normal urinary pigments, is then observed at the zone 

 of contact, while the urine itself remains perfectly clear. If albumin be 



