MECHANICS AND USEFUL ARTS. G5 



by naphthalized gas frightened the gas companies, who foresaw nothing but 

 ruin in the diminished quantity of g is which would necessarily be con- 

 sumed for the production of an equal amount of light. Cold water was 

 consequently thrown upon the project, and the invention has only been 

 of benefit to individuals, and not to the public at large, which might have 

 been the case had it been introduced upon a large scale.' Since this 

 opinion was expressed other inventors have been more successful than 

 Mr. Lowe, and there is no reasoa why the benefits of a rich, pure, and 

 economical light should not be generally diffused. The Artisan then 

 speaks of an invention known as Woodward's gas carbonizer, as giving all 

 the results that could be desired. In this apparatus the gas is made to 

 piss over the surface of benzole or mineral naphtha, receiving its vapor 

 and obtaining a vastly increased illuminating power. It is claimed that 

 in passing over the surface of the fluid the gas comes into contact only 

 with the a ill mnt necessary for ir.s purificitioa, so that the vitality of the 

 spirit is ret lined until it is all consumed. Dr. Muspratt has reported 

 very favorably upon the invention, and photometric experiments have 

 proved thar, taking gas at 4s. &d. per 1,000 cubic feet, there is a saving 

 of more than one-third, the same amount of light being obtained for 

 2s. lid." 



PRACTICAL ICE-1VIAKING MACHINE. 



At the recent meeting of the British Association, Mr. A. C. Kirk 

 gave the following description of a machine invented by him for the 

 artificial production of ice. The machine in question was constructed 

 for Messrs. Young & Co., and superseded another machine used for 

 cooling parafine oil. This latter, Mr. K. said, proving too small for 

 the increasing size of the work, and the use of a material so volatile, 

 inflammable, expensive, and in all respects so dangerous as ether, 

 being a serious drawback, I was requested, in the beginning of 1862, 

 to try if some efficient substitute could not be found. Atmospheric 

 air being the substitute which at once su;<>-ested itself to me as not 



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only safe but inexpensive, I commenced a series of experiments, which 

 at last resulted in a small model, by which I was able to freeze mer- 

 cury. A large machine was immediately proceeded with, which 

 worked so satisfactorily that the use of the ether machine was discon- 

 tinued, and this year at the works a more powerful one has been 

 erected, capable, if applied to such a purpose, of making three tuns 

 of ice in twenty-four hours. I shall now proceed to describe the 

 nature of this machine, which, it will be seen, is allied to the air- 

 engine in the same manner as the ether machine is to the steam-engine. 

 If we enclose a quantity of air in a strong vessel, into the top of which 

 we fix a common air-syringe, and force the piston downwards by hand, 

 we shall compress the enclosed air, which, by the power so spent, will 

 be heated ; and if we now cool the whol'e apparatus down to it.s orig- 

 inal temperature, and allow the air to force the piston gradually back, 

 the air by the effort will be cooled ; but inasmuch as the cooled air 

 will not occupy the same space as the air originally did, the piston will 

 not return to the point at which it was when we commenced, and thus 

 less power will be given out during the expansion of the air than was 

 spent in its compression. It is not necessary that the air be at the 

 atmospheric pressure : if air of greater density be employed, the cool- 

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