200 Miscellanies. 



4. T^egetable matter in Carnelian. — In consequence of some re- 

 marks contained in a memoir of Dufay, published in 1732, relative 

 to the decoloration of carnelian, Gaultier de Claubry heated inl^a 

 porcelain retort some fragments of carnelian with deutoxide of cop- 

 per. There was a sensible emission of gas, which appeared to be 

 carbonic acid, and the fragments were deprived of their color at the 

 surface. In another experiment with pulverized carnelian, the de- 

 velopment of gas was much greater, viz. twenty nine cubic centime- 

 tres from one hundred grammes of carnelian. This appears to leave 

 no doubt of the existence of organic matter in carnelian quartz, and 

 to the presence of which it owes its color. 



At the recommendation of Thenard, the experimenter calcined 

 alone one hundred grammes pf carnelian, which lost in the operation 

 1.169 grammes, and furnished carbonic acid and some inflamma- 

 ble gas, besides an acrid liquor which strongly reddened tournsol : no- 

 ammonia was disengaged from the liquid when treated with lime r 

 the residue was of a greyish white. It follows that the color of car- 

 nelian is owing to vegetable matter. A portion of the loss may 

 be occasioned by the escape of water contained in the stone. — Rev. 

 Encyc. Sept. 1832. 



5. Clay for sculptors. — Sculptors who prepare their models in clay,, 

 have frequently occasion to leave their work for a long time unfinish- 

 ed, and in such cases often experience much difficulty from the dry- 

 hig and shrinking of the material. It is well to know that by the 

 addition of ten to fifteen per cent, of muriate of lime, well worked 

 or kneaded into the clay, it will be preserved for almost any length 

 of time in a moist state, and fit for a renewal of the work without any 

 preparation. — Jour, des Connais. Usuelles. JYov. 1832. 



6. Depuration, of all sorts of oil and of butter, by Curaudau. — 

 This process is unquestionably the best which has been hitherto 

 published. 



Add to one hundred parts of oil ten parts of water, into which one 

 part of flour has been stirred. Shake the mixture well together, and 

 then heat it until all the water is evaporated, or rather until the oil 

 ceases to remain in a state of intimate mixture with the substances 

 vi?hich it held in suspension. It is then purified. In the course of 

 twenty four hours it come out clear, and differs in no respect in qual- 

 ity from that which has been prepared by the best processes : it has 

 lost all its mucilage. 



