501 



ELECTRICITY. 



Eiperi- 



menu of 



Eipcri. 



nitiits of 

 Cmnduh. 



PLAT* 



CCXLVI. 



Fig.ll. 



blue colour. Hence it appears, that the positive effect of 

 an acid is produced with wire, and that the opposite elec- 

 tricity counteracts this effect. Having coated two wire* 

 with sealing wax, so that the extremities only appear- 

 ed, Dr WolListon inserted them into a solution of cop. 

 per, and, upon transmitting a current of sparks be- 

 tween the two wires, the m-gative wire was coated with 

 copper. When the electricity of the wire was rever- 

 ted, the coating of cop|>er was immediately removed. 



The agency of electricity, in combining and decom- 

 posing the gases, has presented chemistry with very 

 interesting results. We are informed in Priestley's ex- 

 periments on air, that Mr Warltire fired a mixture of 

 common and inflammable air by means of electricity, 

 in a close copper vessel holding about three pints. A 

 loss of weight, amounting at an average to two grains, 

 was always perceived, although no air could escape by 

 the explosion. When this experiment was repeated in 

 glass vessels, clean and dry, the inside of the glass im- 

 mediately became dewy. Mr Cavendish repeated these 

 experiments in 1781. He exploded 500,000 grain mea- 

 sures of inflammable air with about 2 ' times that quan- 

 tity of common air, and he, by this means, obtained 

 135 grains of pure water. Mr Cavendish then explo- 

 ded a mixture of 1 9,500 grain measures of oxygen gas 

 with 37,000 of hydrogen gas, and found that they were 

 condensed into a liquor which weighed about 30 grains, 

 which was sensibly acid to the taste, and which yield- 

 ed two grains of nitre. By varying the proportions of 

 the gases, he found, that as he increased the proportion of 

 the hydrogen the acidity of the liquor was diminished, 

 till, with certain proportions, the liquor differed in no 

 respect from pure water. In the repetition of these ex- 

 periments, Mr Cavendish confined the mixture of oxygen 

 and hydrogen in a glass tube A, bent into an angle, as 

 in Plate CCXLVI. Fig. 1 1 ; and which, after being filled 

 with quicksilver, was inverted into two vessels of mer- 

 cury. The gases were then introduced by a small 

 thermometer tube, so as to occupy about one inch and 

 a half in the angular part of the tube. He then con- 

 nected the quicksilver in one of the glasses with an in- 

 Bulated ball, placed at a small distance from the prime 



conductor, while the quicksilver in the other glass 

 communicated with the ground. Mr Cavendish found, 

 that the exjieriment succeeded best when a mixture of 

 five parts of oxygen with three parts of rnnunon air, 

 was used instead of atmospheric air. He then intro- 

 duced a little soap leys along with the air, and having 

 sent through it a current of electric sparks, he conti- 

 nued adding more air as the air was diminished. 'Die 

 soap leys being then poured out of the tube, and separated 

 from tlie quicksilver, were evaporated to dry ness, and 

 left a quantity of salt, which was evidently pure nitrate 

 of potash. In consequence of several learned foreigners 

 having failed in the repetition of this experiment, parti- 

 cularly Van Marum, Troostwyk, I.avoisier, H assent ratz, 

 and NIonge, Mr Cavendish wished to authenticate it in a 

 public manner, and he therefore requested Mr (iilpin to 

 repeat the experiment on the (ith of December 1787, be- 

 fore Sir Joseph Banks and the leading members of the 

 Royal Society. The experiments were in every respect 

 successful ; and though there were some trifling diffe- 

 rences in the proportions of the gases absorbed, yet he 

 obtained the following average result, that seven mea- 

 sures of oxygen unite with nearly three measures of 

 nitrogen to form nitric acid. Van Marum had writ- 

 ten to Mr Cavendish, to learn the cause to which he 

 attributed the failure of the continental philosophers 

 in repeating this experiment. Mr Cavendish replied 

 in a very handsome manner, and communicated to 

 him every information on the subject. Van Marum, 

 however, from some strange misconception, has repre- 

 sented Mr Cavendish, as having refused to comply with 

 his request. Mr Cavendish has replied with great pro. 

 priety to this charge, by publishing his own letter to 

 Van Marum. 



We cannot find room for any further details upon 

 this subject ; but the following Table, for which we 

 are indebted to Mr Singer, will exhibit the principal 

 results which have been obtained. When the mixture 

 consists of inflammable gases and oxygen, the change 

 is generally effected by a single spark ; but in other 

 cases, the current of sparks must frequently be conti- 

 nued for many hours. 



Hxpcri- 

 incnu of 

 Carendiih. 



Experi- 

 ments of 

 Mr Singer 

 on the ile- 



Oi y.iH'S. 



TABLE, shewing the Results obtained by the explosion of mixed Gases by the Electric Spcttk. 



Names of the mixed Gases. 



Results. 



Atmospheric air and hydrogen Water and nitrogen. 



Oxygen and hydrogen Water. 



Chlorine and hydrogen Muriatic acid. 



Muriatic acid and oxygen Chlorine. 



Carbonic oxide and oxygen Carbonic acid. 



Nitrogen and oxygen Nitric acid. 



Sulphurous acid and oxygen Sulphuric acid. 



Phosphuretted hydrogen and oxygen Water and phosphoric acid. 



Sulphuretted hydrogen and oxygen Water and sulphurous acid. 



Oxygen and ammonia ; Water and nitrogen. * 



100 Olefiant gas, and 284 oxygen Carbonic acid and water. 



100 Olefiant gas, and 100 oxygen Carbonic oxide and hydrogen. 



100 Carburetted hydrogen, and 100 oxygen .... Carbonic oxidtrand hydrogen. 

 100 Carburetted hydrogen, and 200 oxygen .... Carbonic acid. 



The figures prefixed to the gases denote the proportional measures which were employed. 



Nitric acid it likewise produced if there is an exccn of oxygen. 



