Sailing and Steam- Vessels. 271 



antarctic voyages. See Expeditions of 1821, 1824, and later 

 ones, where the advantages of warmth, combined with ventila- 

 tion, are clearly shewn. 



A very simple contrivance might be found useful for purify- 

 ing lower decks when unoccupied : a ^rate, formed like a cir- 

 cular basket, hung in gimbals, which, like a pendulum, has its 

 point of rest in the perpendicular. 



The value of lime and vinegar washings and fumigations 

 in destroying the bad effects of impure air, did not escape the 

 older philosophers.* The knowledge of these facts was of 

 vast utility in the days of Howard. Professor Daniel, and 

 other chemists, have, in these times, recommended the use of 

 chlorine gas and chloride of lime for a similar purpose. In 

 combination with ventilating arrangements in ships^ the value 

 of such antidotes — especially where sickness prevails — should 

 not be overlooked. 



If we turn to the graphic pages of Smollett, we may at 

 once perceive, by contrasting his description of a man-of-war 

 with the inspection of one now-a-days, what great improve- 

 ments have been made. But still, much is yet to be done in 

 ship-ventilation generally throughout the world. The air, 

 being invisible, deceives many a one, leading us to consider 

 it pure, while it may be stagnant and corrupt ; hence the i^e.- 

 cessity of impressing the admission of fresh air at all times, as 

 we do light ; and the absurd idea cannot be too soon ex- 

 ploded, of people enclosing themselves in an air-tight box or 

 cabin. With improved means of ventilation of ships and 

 steamers, the energies of all on board will be promoted. By in- 



* Dr Stephen Hales made many experiments recorded in his Statical Essays, 

 London, 1731, vol. i, with a view to clear the air from noxious vapours. He 

 found nothing so efficacious as a solution of potash. He says, page 207, " Sal Tar- 

 tar should be the best preservation against noxious vapours, as being a strong 

 imbiber of sulphurous acid and watery vapour, as is also sea-salt." A solution of 

 caustic alkali will take up fixed air as fast as it is produced. 



The rapid absorption of ammonia by water, and the avidity of fresh lime 

 for carbonic acid, point out the utility of water, with lime recently dissolved in 

 it, for neutralizing the effects of impure air, either by the use of frequent fresh 

 lime-washings, or exposing, in shallow vessels, frequently stirred, solutions of 

 fresh lime. In factories, the sulphate of lime or gypsum is in general use for 

 the absorption of ammonia, or removing the smell of the soil-pipes. 



