10 



SOAP BOILING. 



Boiler for gene- The necessary increase of thickness, and the expence 

 banngite" 1 ' thjtt {t wil1 occasion > can be easily calculated. 

 botiom termi- The effort that an elastic fluid exerts against the sides of 

 pauiigin tubes. tlie con t a ining vessel, is in proportion to the surface of a 

 longitudinal and central section of the vessel, and con- 

 sequently in proportion to the square of its diameter, the 

 form remaining the same. Hence we may conclude, that 

 a steam boiler of a cylindrical form with a flat bottom, 

 which has the same extent of surface exposed to the fire as 

 a boiler of twelve inches in diameter with tubes, should be 

 at least twice as thick as this last, in order to have an equal 

 degree of strength for resisting the expansive power of the 

 steam. 



The boiler which I have the honour of presenting to the 

 Society, is particularly intended to serve as a steam boiler, 

 but it may undoubtedly be applied to other purposes. 

 Having shewn it to M. Auzilly, son of a considerable soap 

 manufacturer of Marseilles, he thought that it might be 

 employed Avith advantage in the making of soap; and from 

 what he told me of the process, and of the boilers em- 

 ployed in that art, I am persuaded that the experiment 

 would succeed perfectly. 



But after all, it remains to be determined, whether it 

 would not be still more advantageous to employ steam as a 

 vehicle of heat in the making of soap, instead of lighting 

 the fire under the bottom of the vessel in which the soap is 

 made. 



The result of an experiment which we arc to make, M. 

 Auzilly and myself, will probably throw some light upon 

 this question. 



III. 



Notice of an Experiment on the Use of the Heat of Steam, 

 in Place of that of an open Fire, in the making of Soap^ 

 By Benjamin Count of Rumford. Read at a Meet- 

 ing of the First Class of the National Institute, the 20th 

 of October, 1806. 



Experiment | HAD the honour of announcing to this assembly, at the 



shewing the , {••''.. iv j. »r i -n * ir 



advantage of » as t- meeting but one 3 that M. Auziliy and myself, were to 



make 



