DESCRIPTION OF A NEW CALORIMETER. £01 



find the same quantity of wat^r at 1.50°, in the proportions 

 used in the calorimeter. Or that upwards of '3 degrees be- 

 came latent, according to Dr. Black ; or, what is more 

 simple and philosophical, went to supply the increased ca- 

 pacity. 



Having performed this and a number of other experiments The result con- 

 at different temperatures, with similar results; and also hav- ^™ ed by ^ ar * 

 irig repeated them before a most accurate and scientific ex- merits. 

 perimenter, for whose opinions I have the highest respect; 

 and having found them all to coincide, I may justly infer, 

 that capacities are not permanent from the freezing to the 

 boiling point. 



I now proceed to«show, that a mean, or an approximation Mean maybe 

 to it, may be produced by a gradual increase of capacity. opacity in- 



If I mix water at 100° with water at 50° in equal propor- crease regulat- 

 ions, a mean of 75* may result. Here 25 degrees with a - v ' 

 larger capacity are lost by the water at 100% which go not 

 only to supply the 25 degrees gained by the water at 50°, 

 but also to fill up that increased capacity, which the water 

 at 50° experienced, to bring its capacity from the freezing 

 point up to an equality of 75° ; and we may easily conceive, 

 that they may 60 nicely* balance*, as even to produce a mean. 

 Dr. Crawford entirely forgot this increased capacity gained 

 by the water at 50°. This may be more clearly demonstrated 

 by two diagrams, the one representing Dr. Crawford's 

 theory, the other mine. 



Suppose a and g in the parallelogram, PI. V, fig. 2, to E> r - Crawford's 

 represent the thermometric range, a b are equal te c e7, and 

 c d to e f and e f to g h ; therefore, if these are equal to 

 one another, and represent the capacities, the capacities are 

 also equal. This may be all very true ; but as similar ef- The proof de- 

 fects may arise from different causes, I will endeavour to fective « 

 show, how a mean may be produced by a progressive increase 

 of capacity. 



Suppose a g, fig. 3, to represent the thermometric range The author's 

 from 32° to 100° ; No. 4 the capacity of 100°, No. 3 that theory * 

 of 75°, and No. 2 that of 50°, although a b is not equal 

 to c </, nor c d to ef but if we produce from g *h to i, 

 g i is equal to c d, and if we produce g i to &, g k is equal 

 to a b. To demonstrate this in another point of view, 



if 



