182 Dr. B. Babington on a Vegetable SubUance 

 Without Snuffing. 



It thus appears, that the maximum of difference has been nine 

 grains in both sets of experiments, while the average in the for- 

 mer is 1 03-91 grains of loss, and in the latter 101-16. The degree 

 of approximation to accuracy in the former experiments may be 

 thus estimated. 



I may incidently add, that it also appears that the consump- 

 tion of material in a tallow candle, snuffed at intervals of ten 

 minutes, is only 2-75 per cent, more than in a candle not snuffed, 

 a difference very inconsiderable, compared with the difference of 

 light produced. 



The ultimate analysis of Piney Tallow being a point of some 

 interest, much pains were taken to perform it with accuracy, 

 and with the aid of my friend. Dr. Dowler, I succeeded in two 

 separate experiments, in obtaining perfectly similar results, which 

 I have so far reason to believe correct. The analysis was per- 

 formed in a glass tube, by means of peroxide of copper, in the 

 usual method, and the water formed was detained in an acute 

 bend of the tube, filled with a given weight of calcined rock crys- 

 tal, coarsely powdered ; and immersed in a mixture of ice and 

 salt. At the close of the process, this portion of tube was cut 

 off, carefully corked at both ends, and immediately weighed. 

 The water was then driven off by the heat of a spirit lamp, 

 and the tube again weighed. I have thought it worth while to 

 mention this method of collecting the water, as I am per- 

 suaded that it is more accurate thus to use mechanical means in 

 detaining it, than to employ muriate of lime, or other chemical 

 absorbents, which attract moisture so easily, as to make it diffi- 



