of Processes in Hie Fine &fut'ffse/ui Jrts. 35^ 



4. Chinese Mode of making Indigo. 



Immerse fifty catties of indigo leaves in a vat of clear water, 

 let them be washed clean, and exposed to the air, after which 

 let them be steeped in water for twenty-four hc^irs. A small 

 jar of burnt shell ashes must then be added, and the whole 

 stirred up with a bamboo. Clear off the scum, and throw in 

 half a catty of the powder of burnt ox-hide ; mix these, and 

 let them settle, and when the surface of the water becomes 

 transparent let it off, and expose the sediment which remains 

 to the open air ; if rainy weather render this impracticable let 

 a charcoal fire be kindled round the vat. When dry the in- 

 digo may be taken out, when it is fit for immediate use. 

 The above quantity should yield upwards of two catties of 

 indigo.-^Erom Asiatic Journal, vol. xxviii. p. 326. 



5. Account of the preparation qfOleocere or a wax for candles 

 from Castor oil. By Mr J. Tytler. 



Nine years ago the following passage, from Brande'^s Ma~ 

 nual of Chemistry, suggested to Mr Tytler a course of ex- 

 periment on the product forming the subject of his paper, viz. 

 " nitric acid, heated in small quantity with any of the fatty sub- 

 stances, renders them harder, and considerably increases their 

 solubility in alcohol. Among the vegetable oils, this change 

 is most remarkably produced upon coco-nut and castor oils, 

 the latter becoming converted into a solid matter, which, when 

 cleansed of adhering acid by washing, resembles soft wax.*" 



On reading this, it occurred to Mr Tytler that oil so con- 

 solidated might have sufficient firmness to form a candle. After 

 a few necessary rude experiments, Mr Tytler adopted an im- 

 proved mode of preparing what he calls oleocere, the great ob- 

 ject being to keep up a uniform heat, and preventing too 

 high a degree of temperature. He thus describes the pro- 

 cess : *' I therefore made water boil in a large fish kettle, and 

 mixed a quantity of castor oil and nitric acid in one of those 

 China jars which are employed to hold preserves. Then care- 

 fully stopping the mouth to prevent the entrance of vapour, I 

 placed this in the boiling water, and kept the whole upon the 

 fire for about an hour, after which I took it off^, and set it by 

 to cool. The effect even exceeded my expectation. It har- 



1 



