312 



Heating water 

 by steam ap- 

 plied to soap- 

 boiling. 



Improvement 

 tin boilers and 

 evaporators. 



SCIENTIFIC NEWS. 



stance were mechanically pressed out of the pores of bodies 

 thus diminished in bulk. In answer to this he has shown, 

 that some cases of condensation are accompanied by the 

 production of cold. Thus solutions of several salts, being 

 mixed with pure water, lose at the same time both bulk and 

 heat. The generation of cold by dissolving salts is a well- 

 known phenomenon, and has been ascribed to the necessity 

 of a solid's absorbing heat when it is converted into a liquid : 

 hut here this explanation will not apply, as the solid is al- 

 ready dissolved, before it is mixed with the water. 



Count Rumford has likewise made a very happy applica- 

 tion of the process of heating water by steam to the manu- 

 facturing of soap. He has succeeded in boiling soap to a 

 proper degree by its means in six hours, which in the com- 

 mon mode requires sixty. He conceives, that this saving 

 of time is partly owing to the concussions given to the mix- 

 ture of oil and lie by the heated vapour forced into it, and 

 there suddenly condensed. 



He has also made a new improvement in boilers for heat- 

 ing or evaporating liquids. This consists in adding to their 

 bottoms several tubes, which descend into the flame, so as 

 to be surrounded by it on all sides; thus increasing the sur- 

 face of the bottom, without adding to its diameter. 



(In our next we shall give an account of the Transactions 

 of the Mathematical Division of the Class.) 



Correction. 

 The Camera Lucida described in our Journal, No. 71, 

 p. 1, is sold not only by Mr. Newman, but also by Messrs. 

 P. and G. Dolxond, St. Paul's Church Yard. 



