Page:Proceedings of the Royal Society of London Vol 1.djvu/268

Rh This probably arose from a minute portion of common salt being contained in them, for the Carrara marble yielded a sensible quantity 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 electrifying 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 hydrogen 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 volatile alkali, was formed. “'hen 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 alkali 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, potash, 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 841%}. grains. The positive wire was inserted into water, contained in an agate cup, and the communication was kept up by moistened amianthus. At the end of the process the glass tube weighed 84:173- grains. The water being evaporated, yielded 1%}.- grains of a mixture of soda, with a. white powder insoluble in acids.

When soluble compounds were put into water, contained in agate