316 Intelligence and Miscellaneous Articles. 



the tube, a part of the carbonate of lead is to be decomposed, in order 

 to expel the portion of air which remains in the apparatus and re- 

 place it by carbonic acid gas; then, after having expelled about 60 

 cubic inches of carbonic acid, exhaust a second time: the combustion 

 is then to be performed in the usual way. The gases are mixed over 

 mercury, in a receiver containing a strong solution of potash. When 

 the decomposition is over, the carbonate of lead is to be again heated, 

 and from 60 to 120 cubic inches of carbonic acid gas are to be formed, 

 so as to drive all the azote from the apparatus, and to convey it to 

 the receiver ; by properly agitating which, all the carbonic acid gas 

 is absorbed and pure azotic gas remains, which may be measured 

 with precision. The only precaution to be taken is that of decom- 

 posing a quantity of matter capable of producing at least from 12 to 

 16 cubic inches of azotic gas — Journal de Chimie Medkale, Oct. 

 1833. . 



ON THE ACTION OF GASES HURTFUL TO VEGETATION. 



M. Macaire, in making some experiments, an account of which 

 he gave to M. De Candolle, mentioned an accident which had de- 

 laved them, viz. the death of several plants by the exhalation of 

 chlorine. M. De Candolle recommended that it should be tried 

 whether this hurtful action occurred during the day or night, 

 observing that chemists who had been consulted on the subject 

 of the exhalations from manufactories, had almost always insisted, 

 that according to their experiments the gas had no action on ve- 

 getables. M. De Candolle suspected that these experiments were 

 probably made in the day, a time in which plants do not absorb gases, 

 which would account for the different results obtained The fol- 

 lowing experiments were made at his suggestion. 



Chlorine.— Plants of euphorbium, mercury, groundsel, cabbage, 

 and sowthistle, which had well taken root, were placed in the morn- 

 ing in a large vessel, in which chloride of lime had been introduced. 

 The roots were steeped outside the vessel : the quantity of chlorine 

 disengaged was far from being sufficient to alter the vegetable tis- 

 sue. Id the evening the plants had not suffered, and the odour of 

 chlorine remained the same. 



The same plants, after having passed the night in the same vessel, 

 to which no chlorine was added, were found quite withered in the 

 morning, except the cabbage, which had resisted. 



The smell of chlorine had entirely disappeared, and was replaced 

 by that of a disagreeable acid. 



This was repeated several times, making the disengagement of 

 chlorine stronger, and the result was the same ; and the plants in 

 the daytime withstood a strong atmosphere of chlorine, while a much 

 weaker dose killed them at night. 



Nitric acid. — The experiment, began at night, with the vapour 

 of nitric acid, showed that the plants were withered in the morning, 

 and some leaves were rendered brown by the action of the acid. 

 The same quantity of acid was tried in the daytime, and though 

 several leaves were made brown, the others were not withered. 



Nitrous acid gas.— This gas appears to be violently poisonous to 



