474 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



timately incorporating the ingredients, as otherwise it will 

 not be transparent. A preponderance of cliromate of pot- 

 ash gives a yellowish shade to the green, and a deficiency in- 

 creases the amount of blue. This varnish, thus colored, pro- 

 duces a very striking effect in japanned goods, paper-hang- 

 ings, etc., and can be made very cheaply. 18 A, August 18, 

 551. 



.REMOVING THE SMELL OF PETROLEUM. 



Professor Stolba publishes w^hat he considers the best meth- 

 od of completely removing from glass or other vessels the 

 smell of any petroleum which may have been previously con- 

 tained in them. This simply consists in introducing a suita- 

 ble quantity of milk of lime and shaking it around thorough- 

 ly, and, after allowing it to stand for a time, repeating the 

 oj:>eration in a few minutes. At the same time the external 

 surface of the vessel is to be washed with a rag dipped in the 

 same substance. Petroleum forms an emulsion with the milk 

 of lime, and can thus be readily removed. If particles of 

 thickened petroleum adhere to the glass, these can be re- 

 moved by washing with fine sand, or by other mechanical 

 means. 



After emptying out the emulsion produced, it is only nec- 

 essary to rinse with water, after which as much chloride of 

 lime as will go on the point of a knife is to be introduced 

 and shaken with water, and then allowed to stand about an 

 hour, the exterior being rinsed off in a similar manner. If 

 the liquids referred to are used hot, this operation will be 

 materially facilitated. 14 C, CCI.,148. 



GERMAN METHOD OF REFINING PARAFFINE. 



A German method of refining parafiine consists in pouring 

 the crude material into an ordinary mixing apparatus pro- 

 vided with a steam jacket, to which the steam is supplied to 

 keep the contents warm. The cover of this mixing appara- 

 tus is made to close securely, to prevent any possible loss of 

 alcohol ; and it is connected with a condenser so arranged as 

 to condense the alcohol as it evaporates, and return it to the 

 mixing apparatus, after the manner of an inverted Liebig 

 condenser. This apparatus is provided at the bottom with 

 a cock for rnnnine oft* fluid substances. The mixing is best 



