62 WRITINGS OF JAMES SMITHSON. 



reddened by it and several other acids, show it not to be 

 indigo. 



Of the black mulberry. 



The expressed juice of this fruit is of a fine red colour. 



Caustic potash made it green, which gradually became 

 yellow. 



Carbonate of soda did not make it green, but only blue. 



Carbonate of ammonia changed it to a vinous red, rather 

 than to blue ; and this redness increased on standing. 



Caustic ammonia made it bluer than its carbonate ; but, 

 on standing, the mixture became of the same vinous red. 



The mulberry juice mixed with carbonate of lime became 

 purple. On filtering, a red liquor passed; and the carbon- 

 ate of lime left on the filter was blue. An addition of 

 whitening to the red filtered liquor did not alter its colour; 

 nor did this second portion of whitening become blue. 

 Heating did not affect the red colour of this liquor ; so that 

 it was not owing to carbonic acid, disengaged from the car- 

 bonate of lime. Caustic potash instant!} 7 made this red 

 liquor a fine green, and gradually yellow. 



Sulphuric acid rendered all the above mixtures florid red. 

 It is remarkable that the mixtures with ammonia, and car- 

 bonate of ammonia, which were become quite vinous red by 

 standing, were made a perfect blue by the sulphuric acid 

 before they were reddened by it. It would hence seem that 

 the red colour, caused by these alkalis, was owing to an 

 excess of them ; and that in a less quantity they would have 

 produced a blue. 



The filter, into which the mixture of mulberry juice and 

 chalk had been thrown, was become tinged blue. Water 

 did not remove this colour. Sulphuric acid made this paper 

 florid red. Caustic potash did not alter its blue colour ; but 

 put on the places made red by sulphuric acid, it restored the 

 blue colour, but did not produce green. 



Future experiments must decide whether this blue matter 



