APPENDIX. 

 " the great expcnce of the apparatus, with the hazard of 

 " the ftill-head being blown off, and the inconveniences 

 " thence arlling:. 



" 5. The ufe of ingredients, which though omitted in 

 " fome experiments in fmall, were neverthelefs erro- 

 " neoufly confidered as effentia] to the making fea- water 

 " fweet and palatable by dirtillation. 



" 6. The inconvenience of a cumberfome apparatus, 

 " calculated only to be eventually ufeful in unexpedled 

 *' diftrefs for water, but conftantly occupying a great deal 

 " of room in a fliip, too neceffary for the ordinary pur- 

 *' pofes to be fpared for that objed. 



" Having fpecified the principal defers of the feveral 

 " methods hitherto propofed for making fea water frefh, 

 " it will be proper before ftating the advantages of Doftor 

 " Irving's method, to confider briefly the principles of 

 " diftillation in general, and the chemical analyfis of 

 " fea water. 



" Water, in an exhaufted receiver, rifes in vapour more 

 '* copioufly at 180° of Fahrenheit's thermometer, than in 

 *' the open air at 212°, which may be confldered as its 

 " boiling point. 



" It therefore follows, that any compreflion upon the 

 " boihng fluid checks the vapour in rifing, and confe- 

 " quently dimlnifhes the quantity of water obtained. This 

 " is clearly examplified in the fleam-engine, where the 



I i 2 " confumption 



Tf 



