6 TiMEHRI. 



are so interesting and illustrate the foregoing so clearly 

 that a piece has been cut off and sent for your observa- 

 tion; a sketch, Fig. i, has also been made, on which it 

 will be noticed that the corrosion extends exa6lly one 

 and a half inches from the top tube plate down, and that 

 beyond that the iron shows only one-sixteenth of an inch 

 corrosion, the zone of a6tive gas being clearly and dis- 

 tindlly shown, the bottom of the rod in conta6l with the 

 water was a little more corroded than the centre of the 

 rod, but nothing like the top part. Tubes (B and F) 

 were cut from triples after three years' work, these also 

 show plainly the efredl of the aftive top corroding zone. 

 Tube (C) is another similar example, except that it was 

 originally tinned, in this case the corroding zone is quite 

 as marked, besides this there are pittings and longitu- 

 dinal grooves also corroded in, doubtless these pra6lical 

 examples will be interesting to chemists, who by letting 

 light on the subject and giving engineers an antidote 

 will confer a boon on planters. 



In the two cases under consideration the copper water 

 pipes have been renewed oftener, as a matter of fa6l 

 some 2^ inch wrought iron gas pipe, used as a tempo- 

 rary water pipe, was eaten out repeatedly in three days, 

 whilst on a neighbouring estate with pra6lically a dupli- 

 cate evaporator and exa6lly the same process of manu- 

 fa6lure and chemicals used, a wrought iron pipe has 

 been satisfa6lorily used for years ; these are fa6ls. Will 

 some one explain the cause ? The vapour is derived 

 from the cane juice after it leaves the eliminators; the 

 most a6live is given off in the third or last vessel of the 

 evaporator; on some estates it is light and harmless, 

 whilst on other estates the cane juice, though treated in 



