CHEMICAL SCIENCE. 291 



members of the committee for the chemical nrts appointed by the Societe 

 Industrielle of Mulhouse, to report upon the memoirs of M. Schlumber- 

 ger, to try the eifect of exposing a piece of cloth, treated with alloxan, to 

 the vapors of ammonia. The result confirmed their anticipations ; for the 

 color was immediately produced without the necessity of ageing the cloth 

 after its impregnation with the alloxan. There can, therefore, be no doubt 

 that the best results will be obtained in future by the employment of am- 

 moniacal vapors ; for, besides the saving of time, there will also be a saving 

 of alloxan. This substance is very liable to decompose, especially in the 

 presence of even minute traces of reducing agents, such as protochloride 

 of tin or sulphurous acid ; traces of the latter substance always remain in 

 the cloth after the operation of bleaching, no matter how well washed it 

 may be, and would be quite sufficient to prevent the formation of the 

 murexide. 



As yet, all the attempts that have been made to communicate the murex- 

 ide-purple to cotton or silk have failed, that substance having an affinity appa- 

 rently only for wool, to which it gives a permanent and durable dye. Sunlight, 

 so destructive to other purples, appears to have but little action upon that 

 of the murexide ; a piece of cloth dyed of a rose color had its tint scarcely 

 altered by exposure to the full action of the strongest sunshine during two 

 days, and the color was only fully discharged by an exposure of more 

 than two months. Boiling water and steam completely destroy the color 

 produced upon cloth mordanted with salts of tin ; the decoloration com- 

 mences in boiling water at a temperature of about 158 F., and augments 

 with the increase of temperature. This destruction of the dye is caused 

 by the action of the mordant ; for cloth dyed without the use of mordant not 

 only supports to a certain extent the action of boiling water, but even ac- 

 quires a more uniform, and perhaps a more beautiful and deeper, tint than 

 that given by prepared woollen fabrics. Further experience may show that 

 hot water and the application of ammonia alone may be advantageously 

 substituted for the mordanting and the passage over heated cylinders. 



Cold alcohol or ether have no action on murexide purple ; the former 

 liquid destroys it at boiling temperature, without being colored purple as 

 is water. Alkalies, especially in a caustic state, are very destructive to it ; 

 if a piece of cloth dyed with murexide be dipped into a solution of caus- 

 tic soda, it assumes a violet -blue color, and is then decolorized. Soap, 

 acting as a weak alkali, after a time alters it. Chlorine has no immediate 

 action upon it, at least not in weak solutions. Acetic and oxalic acids are 

 not sufficiently energetic to immediately discharge the color. Hydrochloric, 

 nitric, and sulphuric acids act as decolorizers ; nevertheless the latter acts 

 less quickly than the first two ; and what is singular, the color almost de- 

 stroyed by sulphuric acid reassumes a rose-violet by immersing the tissue 

 in ammonia. 



Bichromate of potash, chlorate of potash, acetate of lead, acetate of 

 alumina are without action upon murexide. This is not the case, 

 however, with reducing compounds, such as protochloride of tin, 



