262 Mr. G. C. Foster on Chemical Nomenclature, 



the engine required to do it is about 3 per cent. less. The 

 angular velocity of the new wheel will be greater than that of 

 the old in the ratio of 1*175 to 1, or nearly in the ratio of 6 to 5. 

 We may conclude, then, that for a velocity of ten miles an hour 

 in a steamer with paddle-wheels of 15 feet radius, the number 

 of revolutions a minute should not be less than 18: and with 

 this number the relations between the resistances and moments 

 are those given above, which show an advantage in favour of 

 the new wheel. With a less number of revolutions the part of 

 a float nearest to the axis will tend to stop rather than to propel 

 the boat. For a velocity of 18 miles an hour, the number of 

 revolutions a minute in the new wheel should not be less than 

 30, for the same reason • and then the same hold is obtained on 

 the water as in the ordinary wheel making 25 revolutions a 

 minute, and that with less power of engine. By still further 

 increasing the angular velocity in the new wheel as compared 

 with the old, so that the number of revolutions a minute are as 

 3 to 2, the ratio of the resistance to the power producing it is 

 10 per cent, greater in the new wheel than in the old. Since 

 it appears that the angular velocity of the new wheel may be 

 made much greater than that of the old (provided marine 

 engines will admit of such an increase in the rate of revolution) 

 without causing the floats to slip through the water, it follows 

 that this increase will give the new wheel a great advantage over 

 the old with regard to speed. 



XXXVII. On Chemical Nomenclature, and chiefly on the use 

 of the word Acid. By G. C. Foster, B.A., Lecturer on Na- 

 tural Philosophy in Anderson's University, Glasgow** 



IN forming a nomenclature for any science, two distinct 

 requirements must be kept in view as having each to be 

 supplied. In the first place, a convenient general language 

 must be provided, to serve as a medium for the ordinary every- 

 day transactions of the science ; and in the second place, there 

 must be what may be called the legal language of the science, 

 — a language whose terms are, as far as possible, strictly defined, 

 and have an exact and generally recognized value. It is this 

 second stricter language which constitutes the more technical 

 part of scientific nomenclature, and it is this alone which it is 

 either desirable or possible to alter or reform in accordance with 

 any particular state of scientific opinion. The general language 

 of a science will always, in the main, take care of itself; and at 

 any given period it usually contains a large admixture of terms — 

 once technical, but now no longer used for purposes of accu- 

 * Communicated by the Author. ; 



