146 Correspondence of 



a retort closed with a piece of paper. The infusion is then 

 passed through a woollen sieve ; the residue was^hed in cold 

 water, decanting all that remains suspended in the water ; the 

 latter portion is then to be infused in the same manner in pure 

 water, and both infusions are to be mixed. Tb.e whole is to 

 be heated for an instant, and then allowed to su'oside for twenty- 

 four hours, when it is to be filtered again : gum and .<ugar are 

 then to be added ; and when they are dissolved, the whole is to 

 be once more passed through the sieve. The ink is then to be 

 mixed with the oxide or red sulphate, l)ut neither the acidu- 

 lated nor osidulated sulpiiate ouglit to be used. The whole being 

 then shaken, may be put into a stone bottle and corked with a 

 paper stopper. 



Not only is the ink thus prevented from being corrupted, but 

 it loses another bad property, namely, that of thickening. The 

 acid of the vinegar is coml)ined as a mucous kind of acetate with 

 the mucilaginous n;atter, and precipitates it ; the vinegar is very 

 rriucii softened in this infusion by the connexion which its acid 

 parts form vvith the mucus. The thickening of the ink arises 

 from the sulphuric acid rendered free, precipitating this body. 

 The mucus of the gum arable scarcely undergoes this change at 

 all. I consider myself fortunate in having so well succeeded 

 in this preparation. 



I lately made a very singular experiment. I was directing on 

 some red oxide of mercury scarcely heated to 30° of Reaumur, a 

 jet of hydrogen gas from a bladder. I wished to obtain water, 

 but did not obtain any, but the red oxide became white. I 

 heated it more fiercely, and it was red hot before the steam of 

 the water appeared; and then instead of reduced mercury there 

 remained black oxidulate, which I had much difficulty in de- 

 oxidating. 1 forgot to say, that during the process the matter 

 instead of becoming of a dull purple colour became yellow only. 



Having repeated the experiment at a low red heat, I obtained 

 water and concrete reduced mercury which resisted the fire a long 

 time, giving out hydrogen and liquid metal. I operated with a 

 double crucible, the upper one being of glass. My first idea of 

 this phcenomenon was incorrect; for I had, like Dobereiner and 

 Davy, made of the mercury a new metal concrete even in the 

 fire, by incorporating an overplus of hydrogen at first with its 

 oxide, and afterwards with the reduced metal. 



Hence came a metal more intense, and which will not be more 

 deoxidable in the fire, if it does not remain decomposable in the 

 hydrogen added. We may regard this super-hydrogenation, 

 when it takes place upon the oxide, as a mineral organization, 

 and the sanie with that which carbon undergoes ir. plants, and 



azote 



