ON IHE USES OF SALTING VEGETABLES. 25S 



[18 cub. inches], notwithstanding the experiment occupied 

 24^ minutes, &c." Bat the duration of the experiment 

 could have no etFeet on the result as tar as it was owing to 

 the cause in question, since this is simply the dilference be- 

 tween the air retained in the lungs previous to the experi- 

 ment and after its conclusion, whether the experiment con- 

 sisted of a singfe inspiration and expiration, or of a thou- 

 sand. C. 



XIIL 



Ohservatiolis on the Pickle of Violets, considered vs a Re- 

 agent ; and on the Adcantage of Salting Vegetable!)', from 

 which Dislilkd Waters are intended to be made : by Mri 

 De.scrojizilles, Sen.* 



I.,\,rr 

 N chemical analyses, when we wish to detect the pre- Sirup of vrG.let» 

 sence of uncombined acids or alkalis, or of alkaline sub- ^^^ '" spoil. 

 carbonates, the most usual test is sirup of violets. But 



this has some inconveiiiencies, as it is very apt to spoil. Ac- . ,. . „ 



J r r ^ saline iofii. 



cordingly it occurred to me to try what 1 call pickle of vio- sion preferabi* 

 tets, and I found it answer exti-emely well. The following 

 is my mode of making it. 



On the petals of the violet slightly pressed into a small Mods of pra- 

 pewter measure, pour double their weight of boiling water, P^""* ' 

 and stir them together. Cover over the measure, and expose 

 it for a few hours to a heat somewhat greater than that of a 

 waterbath : after which let the liquor be strongly pressed 

 out through a very clean lirven cloth. Weigh the infusion 

 accurate!}', and add to it one third of its weight of common 

 salt, stirring .t till this is dissolved. Very fine white salt 

 should be chosen, as this contains little or no earthy muri- 

 ate, which would be detrimental to the colour. In a small 

 phial corked this will keep without alteration, though ex- 

 posed to various degrees of temperature, and even to the 



♦ Annales d« Cbimie, vol. LXVII, p. 80. 



rays 



