Papers on Subjects Connected with the Duties of the Corps of Royal Engineers. [New Series] Volume 5 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1856 Excerpt: ...of this machine over the ordinary diving bell is that it is independent of the surface, both as regards its supply of air, and its means of ascent and descent. The supply of air is, in practice, derived entirely from the reservoirs B, B', into which the air is condensed by pumping, previous to the descent. The carbonic acid gas exhaled from the lungs of the occupants being heavy, falls to the bottom, and if the machine descends in running water, is absorbed by and carried away in the current; but in still water, as the water can only dissolve a small quantity of the gas, an ingenious though simple method of getting rid of the remainder is resorted to. The air is passed through lime water, by means of a common bellows, and thus freed from the carbonic acid it contains, which is precipitated as carbonate of lime. The operation is continued for a quarter of an hour, and an equal time is allowed to elapse before it is recommenced. A little potash is required to make the lime dissolve, and as much lime is used as will saturate about six gallons of water. Such a mixture will last for a long period. The carbonic acid gas being thus completely absorbed by the lime, the atmosphere of the machine ceases to possess any hurtful property, and requires nothing more than its hourly supply of puie air from the compartments B, B' to make it healthful. Dr. Payerne states that, in practice, he has never had occasion to employ other than these means, and that he has found them amply sufficient in all cases for a day's work. In remaining under water for a more lengthened period, it would become necessary to add from time to time a certain amount of oxygen. The nitrogen, with the exception of a trifling quantity, which goes to form ammonia, is exhaled from the system in the same...