CHEMICAL SCIENCE. 247 







of copper acts as a solvent only from the excess of oxide of copper present. 

 Mr. Schlossberger finds that the solvent power increases with the proportion 

 of copper, and that the hydrate of copper dissolved in ammonia acts better 

 than the sulphate. The cupro-ammoniacal liquid does not dissolve gum, 

 dextrine, starch, while it does dissolve filtering paper. The salts, and espe- 

 cially the alkaline salts, precipitate this solution of cellulose, and sulphate of 

 copper has the same effect. The precipitate shows no trace of organization 

 or crystallization; and it does not appear to differ in percentage composition 

 from that of cellulose. These same alkaline salts do not precipitate the solu- 

 tion of silk, and the fact may be made the basis of a process for sepai'ating 

 silk from cotton. The solution of cellulose is precipitated also by alcohol, a 

 concentrated solution of honey, gum Arabic, or dextrine. The cupro-ammo- 

 niacal liquid has no action on pyroxilline or collodion. Inuline, chitine, 

 conchyoline, are insoluble in it. Mr. Schlossberger has found that the am- 

 moniacal hydrate of nickel, XiO HiX, acts like the salt of copper. The 

 solution of silk is, however, a fine blue in the latter, and a yellowish brown in 

 the former. Correspondence of Silliman's Journal. 



The ammoniacal solution of oxide of copper and ligneous fibre, cotton, 

 etc., is now coming into use as a substitute for collodion in photography. 

 Most of the basic salts of copper, and its hydrated oxide, give blue solutions 

 with ammonia, all possessing the remarkable property of dissolving the 

 cellular tissue, the basic carbonate of copper in a higher degree than the rest. 

 To prepare it, a solution of blue vitriol is precipitated with carbonate of soda, 

 the precipitate transferred to a filter, on which it is washed and then dried in 

 the water-bath, coarsely poAvdered and shaken in a well-stoppered flask, with 

 aq. ammonia of spec, gravity = 0'94-j, which is found to be the best strength 

 for this purpose, the resulting solution being a better solvent than that of 

 any other salt of copper. The portion of this liquid which acts as the dis- 

 solving medium for the ligneous membrane is undoubtedly the ammoniated 

 oxide of copper, not the uncombined alkali or acid. This is proved by the 

 very process used by the discoverer of this interesting phenomenon, Peligot, 

 who employed the spirits of ammonia, agitated and digested with copper 

 turnings. A small proportion of sal ammoniac hastens the solution of the 

 metallic copper, which latter may be advantageously replaced by precipitated 

 copper. According to Peligot, these ammoniacal solutions take up a quantity 

 of cellulose equal to that of the copper held in solution. SCHWEIZER, 

 Schweizer Zeitschr. fur Pharmacie. 



ON THE AMMONIACAL SOLUTION OF PEOTOXIDE OF NICKEL, AS 

 A MEANS OF DISTINGUISHING SILK AND COTTON. BY PROF. 

 SCHLOSSBEEGER. 



The violet-blue solution of freshly precipitated hydrate of protoxide of 

 nickel, exerts an extremely remarkable action upon silk. If silk threads be 

 brought in contact with a drop of this solution under the microscope, pecu- 

 liar vermicular movements are observed in it, and at the same time they 

 swell up considerably, and acquire a yellow color. Soon afterwards the out- 

 lines become pale, in part (with raw silk) accompanied by considerable infla- 

 tions or ruptures of the external envelops of the fibres, and finally complete 

 solution take place. If silk be thoroughly kneaded up in a test-glass by 

 means of a glass rod with the blue solution of nickel, it soon becomes of a 

 brownish-yellow color, resepibling that of hydrated oxide of iron ; it then 



