104 Chi the Means most proper to be resorted to 



more mischief, should a vessel of it by accident be broken 

 or spilt, than as much strong vinegar. No good objectioa 

 can therefore be offered against its use on the score of its 

 being dangerous. 



The chalk should be in powder, cither in a dry state or 

 diffused in water, and the vessels containing it should be 

 so disposed and arranged in regard to those containing the 

 diluted oil of vitriol, that, without needing to hunt for and 

 arrange them in the hour of danger, (when the hurry and 

 alarm might make it impos^ible to get at them, or io n)ake 

 a proper use of them when found,) no more might be ne- 

 cessary than to turn a cock, somewhere near the cabin, 

 under the immediate eve of the commander or some intc^l- 

 ligent officer to allow the acid to convey itself through 

 leaden pipes into the vessels containing the chalk or lime-> 

 stone. 



The moment the sulphuric acid comes in contact with 

 the chalk, the latter will be decomposed and part with the 

 carbonic acid, one of its constituent principles, which will 

 escape in the gaseous form, while the lime, its other prin- 

 ciple, will remain united to the sulphuric acid. 



All the articles connected with this process should be 

 made of lead, or lined with it, as the sulphuric acid exer-. 

 cises little or no action on that metal, which renders it pre- 

 ferable to every other material for the purpose. 



The ways in which the parts of such an apparatus might 

 be arranged to advantage are so various, that to insist on 

 any one in particular is unnecessary. The princii)}eof the 

 arrangement is all that need be noticed here. The vessel 

 or vessels containing the acid must be in a higher situation 

 than those containing the chalk or unburnt lime. The 

 latter may be in the hold, or in any situation lower than the 

 former; and pipes of communication, that can be opened or 

 shut at pleasure by turning a cock, as already mentioned, 

 must pass from the vessels containing the acid to those in 

 which the chalk is. 



The latter, if in the hold, should have perforated covers, 

 that the fixed air, when liberated from the limestone or 

 chalk by the action of the sulphuric acid, may have a free 

 escape. If above any of the decks, a hose or tube should 

 pass from their tops down to the hold and lower decks for 

 the liberated gas to descend through. These tubes should 

 be secured from injury by covering them with planks, or 

 casing them at the time of their fitting up. 



Such an apparatus as is here recommended would be found 

 much more simple than it can possibly appear to be from a 



description. 



