MECHANICS AND USEFUL ARTS. 85 



By combining the application of this fact with a simple, ingenious, 

 and very efficient method of aerating the distilled water, Dr. Nor- 

 mandy has succeeded in effecting one of the most important and 

 recent improvements in the purification of water, and one which has 

 already received several applications in connection with the military 

 service, though its benefits will unquestionably be far more exten- 

 sively experienced by all branches of the marine service. The follow- 

 ing is substantially the action of Dr. Normandy's apparatus: The 

 heat of the steam which passes over from the boiler into the appara- 

 tus is made to perform, in succession, two important operations. In 

 the first instance, it is applied to the production of a fresh quantity of 

 steam (equal in volume to that obtained from the boiler) ; this is very 

 simply effected by employing so small a volume of water for condens- 

 ing the first steam (which always enters the apparatus under a slight 

 pressure) that the former is speedily raised to a temperature at which 

 it is rapidly converted into steam, and at which it is maintained by 

 suitable arrangements. This second portion of steam is made to pass 

 into another condenser, differing in its arrangement from the first in 

 this, that the condensing water employed in it is very gradually but 

 continuously replaced, so tl)at, though its temperature is not raised to 

 the same extent as that in the first condenser, it becomes sufficiently 

 hot, before it passes out of the apparatus, to part with nearly the 

 whole of the gaseous matter which it contains in solution. The gas 

 thus expelled from the water is made to mix with the steam produced 

 in the apparatus, as described just now, so that the latter, on its con- 

 densation, furnishes distilled water, thoroughly saturated with the 

 gaseous matter derived from the original water. This aerated pro- 

 duct, in passing into a refrigerator, mixes with the first product, 

 which is simply ordinary distilled water, and the whole then flows 

 through a cylindrical vessel filled with wood-charcoal, from which it 

 issues as bright and sparkling water, completely free from any trace 

 of the usual flavor of distilled water, and as palatable as the best 

 spring water. An apparatus of this kind was employed to supply the 

 German Legion with water at Heligoland during the late war ; two 

 of large size have been dispatched to China for the hospital ships, and 

 I believe that many cases will occur in which it will be applied with 

 great benefit to the supply of wholesome water to troops. 



Grant's Cooldny Apparatus for the field, which is a great improve- 

 ment as regards economy and comfort, and which has been introduced 

 into the British service, consists of a number of Ion*? cylindrical ket- 



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ties (which may, if necessary, be made to serve the purpose of pon- 

 toons), and which are used in the following manner : Four trenches 

 are dug in the form of a cross, each of sufficient length to receive two 

 kettles placed end to end, and of such other dimensions that the ket- 

 tles shall be supported by the sides of the trenches, of which the 

 lower portions are thus converted into flues, all communicating with a 

 central sheet-iron chimney. The kettles are, therefore, heated by 

 kindlinsc a fire at the extremity of each trench, and with eio-ht of 



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these kettles, arranged in this manner, sufficient food for eight hun- 

 dred men can be cooked in about three hours with a very small expen- 

 diture of fuel. 



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