376 Dr. Neubauer on Catechu and its Acids. 



It was found by Fischer that nitrite of potash mixed with solu- 

 tions of cobalt gave a crystalline yellowish precipitate. This 

 body has been examined by Stromeyer, and he considers it to be 

 composed according to the formula 



Co^ 03 2N03 + 3K0 N03 + 2H0. 



It is formed when a neutral cobalt salt is mixed with nitrite of 

 potash, oxygen being absorbed, thus : — 



2CoO, S03 + 5(KON03)+0 + 2HO = Co2 0^2N03 

 + 3(K0 N03) +2H0 + 2(K0 SO^). 

 This reaction is of great use in detecting cobalt, as many special 

 experiments sufficiently prove. Stromeyer gives a method for 

 the preparation of nitrite of potash, which consists in fusing salt- 

 petre with lead in the proportion of 1 to 2 ; but it seems to pos- 

 sess no great advantages over the ordinary methods. 



Prof. Schmid of Jena communicates that he has detected urea 

 in diabetic urine. 



Dr. Vohl of Bonn gives the results of experiments made with 

 the view of employing hyposulphite of soda as a precipitant for 

 the heavy metallic oxides ; but they do not show that this body 

 has any decided superiority over the reagents at present in use. 



In the December Number of the same journal, M. von Bibra, 

 in a communication "On Hair and the substance of Horn," states 

 that he has not succeeded in extracting any colouring matter from 

 these substances ; and thinks that the colours, especially of the 

 various kinds of hair, depend on the structure, and that this is 

 a question for the microscope. He also adduces a large number 

 of determinations of the sulphur, fatty matter, and inorganic 

 constituents contained in these substances. From these it is 

 impossible to draw any useful general conclusion. 



Dr. Neubauer furnishes the results of an investigation "On 

 Catechu and its Acids," which he undertook in the hope of find- 

 ing a similar connexion between catechuic acid and catechutannic 

 acid to that which Strecker found to exist between gallic acid 

 and tannic acid. He had hoped that by treating this acid with 

 sulphuric acid it would split up into catechuic acid and sugar ; 

 but neither catechuic nor catechutannic acid afforded any sugar 

 when thus treated. 



He notices that the various kinds of catechu arise from the 

 different modes of preparation, and that the catechuic acid con- 

 tained in them all is of the same composition, C'^ H*^ 0*°. 



In this Number of the Annalen is given an abstract of the 

 results which Piria has obtained in his investigation of Populine. 



