APPENDIX, 



*' and elafticity of the vapour confined by this conftruflion. 

 " In the mean time, the external furface of the pipe 

 " communicates heat to the water in contaQ with itj 

 *' which, inftead of being entirely carried off, mixes with 

 *' the furrounding fluid, and heats the whole, rendering 

 " it unfit for condenfing the vapour within; efpecially 

 *' when it is confidered that the fubftance of the pipe is at 

 " leaft a quarter of an inch thick. 



*' From what has been faid, it is plain, that the quan- 

 " tity of diftilled water will be leffened in proportion to 

 " the refinance made to the afcent of the vapour, while 

 " the difficulty of condenfation will be greatly augmented, 

 ** in confequence of the increafed heat and elafticity of 

 " the vapour. But thefe difadvantages, i owever great, 

 " refpecling the mode of diitillation, give rife to another 

 " evil of a itill more important nature, as affeding the 

 " diftilled fluid with a noxious l}tir7it tajieox empyrewna\ 

 " occafioned by the vapour, highly heated, pafling over 

 " fo much furface of metal, viz. the flill-head, crane-neck, 

 "and a pipe of fix or feven feet in length, before it reaches 

 " the water in the worm tub. 



" Having difcufied the fubje(El of diftillation, we come 

 now to treat of the chemical analyfis of fea water. 



213 



«c 



" Sea-water, 



