248 



This probably arose from a minute portion of common salt being 

 contained in them, for the Carrara marble yielded a sensible quan- 

 tity on analysis ; and on repeating the electrifying of the water in 

 the cup formed of it, the presence of soda became less visible every 

 time, and at length disappeared entirely ; but the production of lime- 

 water was uniform.. A bit of glass added to water, which was elec- 

 trifying in the gold cones, caused it to exhibit almost immediately 

 the presence of soda. 



In every instance nitrous acid was uniformly found in the positive 

 cup, which appeared to proceed from the combination of nascent 

 oxygen with the nitrogen of the common air absorbed by the water. 

 The longer the operation was continued, the more acid was produced, 

 arising from the air which continued to be absorbed. Volatile alkali 

 was also constantly formed, from the combination of the nascent hy- 

 drogen with the nitrogen ; but it soon attained its utmost limit, as 

 hydrogen during its solution in water seems to expel nitrogen. When 

 water was electrified in vacuo scarcely any nitrous acid, and no vo- 

 latile alkali, was formed. When electrified in a receiver filled with 

 hydrogen (the common air originally contained in the water having 

 been extracted by the air pump), neither nitrous acid nor volatile al- 

 kali was found in the water. 



In all these processes, the acid matter collected in the water round 

 the point transmitting the electricity, and the alkaline matter round 

 that which received it. When water was even electrified in two cups 

 made of sulphate of lime, it was found that the water connected with 

 the positive wire contained sulphuric acid, while that in the other 

 cup was a pure and saturated solution of lime. Similar effects were 

 produced when use was made of cups of sulphate of strontian, fluate 

 of lime, or sulphate of barytes. It also appeared, that very minute 

 portions of acid or alkaline matter might be disengaged by this 

 means from solid combinations, consisting principally of the pure 

 earths. When cups were used made of a basalt which contained 

 3^ parts of soda, and nearly half a part of muriatic acid, with fifteen 

 parts of lime in the 100, oxymuriatic acid was found in the positive 

 cup, and a mixture of lime and soda in the other. A cup of compact 

 zeolite, containing seven per cent, of soda, yielded soda and lime to 

 the water connected with the negative wire. Lepidolite yielded 

 potash, and vitreous lava from Etna yielded a mixture of soda, pot- 

 ash, and lime. 



Mr. Davy attempted to ascertain whether the weight of the alkali 

 obtained, agreed with the weight lost by the substance operated upon. 

 Water was electrified negatively for four days, by a current from 150 

 plates, in a glass tube that weighed 84-! VV grains. The positive wire 

 was inserted into water, contained in an agate cup, and the commu- 

 nication was kept up by moistened amianthus. At the end of the 

 process the glass tube weighed 84 ^-/T grains. The water being eva- 

 porated, yielded T VV grains of a mixture of soda, with a white powder 

 insoluble in acids. 



When soluble compounds were put into water, contained in agate 



