On Chemkal Equivalents. 1 1 1 



to their weights, that the series of numbers placed on a sliding 

 scale can at pleasure be moved, so that any number expressing 

 the weight of a compound, may be brought to correspond with 

 the place of that compound, in the adjacent column. The ar- 

 rangement is then such, that the weight of any ingredient in its 

 composition, of any reagent to be employed, or precipitate that 

 might be obtained in its analysis, will be found opposite the 

 point at which its respective name is placed. 



If the slider be drawn upwards, till 100 corresponds to mu- 

 riate of soda, the scale will then show how much of each sub- 

 stance contained in the table, is equivalent to 100 of common 

 salt. It shows, with regard to the different views of this salt, 

 that it contains 46*6 dry muriatic acid, and 53" 4 of soda, or 

 39'S sodium, and 13'6 oxygen ; or if viewed as chloride of so- 

 dium, that it contains 60*2 chlorine, and 39"S sodium. With 

 respect to reagents, it may be seen, that 283 nitrate of lead, 

 containing 191 of litharge employed to separate the muriatic 

 acid, would yield a precipitate of 237 muriate of lead, and that 

 there would then remain in solution, nearly 146 nitrate of soda. 

 It may at the same time be seen, that the acid in this quantity 

 of salt would serve to make 232 corrosive sublimate, containing 

 185*5 red oxide of mercury; or make 91-5 muriate of ammonia, 

 composed of 62 muriatic gas (or hvdromuriatic acid), and 29"5 

 ammonia. The scale shows also, that for the purpose of obtain- 

 ing the whole of the acid in distillation, the quantity of oil of 

 vitriol required is nearly 84, and that the residuum of this distil- 

 lation would be 122 dry sulpliate of soda, from which might be 

 obtained, by crystallization, 277 of Glauber salt^ containing 155 

 water of crystallization. These, and many more such answers, 

 appear at once, by bare inspection, as soon as the weight of any 

 substance intended for examination is made, by motion of the 

 slider, correctly to correspond with its place in the adjacent co- 

 lumn. Now surely the accurate and immediate solution of so 

 many important practical problems, is an incalculaljlc benefit 

 conferred on the chemist. • 



With regard to the method of laying down the divisions of this 

 scale, those who are accustomed to the use of other sliding rules, 

 and are practically acquainted with their properties, will recog- 

 nise upon the sli<ler itself, the cf)mmon Giniter's line of nnml>ers, 

 (as it is callefl) and will be satisfied, that the results which it 

 gives are the same that would be obtained by arithmetical com- 

 putation. 



Those who are acquainted with the doctrine of ratios, and with 

 the use of logarithms as measures of ratios, will understand the 

 principle on which this scale is founded, and will not need to be 

 told, that all the divisions are logometric j conscciucntly, that 



the 



