26a Additional Remaris on Galitanic EkSlricity, 



was applied ; befides the wire on the zhic fide being removed from the platCi and plunged 

 in a cup containing water, whiift a copper wire reaching from the cup to the zinc plate, 

 preferved the communication, gas ilTued copioufly from the platina wire, and the copper 

 was corroded as ufual. 



The acid was then diluted with an equal bulk of water, or rather more, and being 

 again introduced into the tube, flill rery little gas was produced on either fide. From 

 thefe fa(Sl:s it would appear that the nitrous acid is fo perfeft a conductor of this influence 

 as to tranfmit it like metals, without being at all acted upon by it. This may poffibly be 

 owing to the great proportion of oxygen which enters into its compofition, for we have 

 already remarked, that all fluids, containing very little or no oxygen, are perfedl non- 

 condudlors, or nearly fo ; and it is probable that the conducting fluids are more or lefs fo 

 in proportion to their quantity of oxygen. 



It was remarked in a former paper, that it was highly probable, the nitrous, or fomc 

 Other acid, was produced at the zinc wire, I (hall now bring forward fome additional fadia 

 and arguments in fupport of this hypothefis. 



ift. If the tin£lure of litmus be introduced into the bent tube already mentioned, and 

 platina wires employed ; after fome time the whole of the litmus in the leg of the tube 

 connected with the zinc wire will be rendered perfectly red, and in fome places the colour 

 even partially dcftroyed, a well known e.?{eQt of the nitrous acid on blue vegetable in- 

 fufions. But if the litmus be mixed with a little of any pure alkali, no fuch change of 

 colour can be perceived. 



2d!y. All metals which are diflblved or adled upon by the nitrous acid, are likewife very 

 quickly corroded by the galvanic influence ; but fuch as are not afled upon by this acid 

 are not at all afFe£ted by this influence. Of this we have ftriking examples in filver, 

 mercury, gold, and platina; the firfl: two are readily a£ted upon both by the nitrous acid 

 and galvanifm, but the two laft by neither in any fenfible degree, and pnflibly not at all 

 when perfeftly pure. Now filver, which has always been confidered as a perfe£l metal, 

 cannot be oxydated by any of the ufual methods, any more than gold, yet this influence' 

 has fully as great an efFeft upon it, as upon copper; which we conceive may be explained 

 in the following manner : — Let us fuppofe that a little nitrous acid is produced on the 

 furface of the filver, the metal muft in this cafe be in fome degree a£ted upon by it, and 

 this acStion will ncceflarily difpofe it to unite with oxygen, which, being thus in its 

 nafcent flate, mud readily combine with the filver, and form infoluble nitrate with excefs 

 of oxyde, which will, confequently, be but little foluble in water. Now that this is really 

 the cafe, we think is rendered probable by the following experiments : 



A fmall wide mouthed bottle was filled witli a dilute folution of pure pot-afh, and 

 inverted in a cup, containing fome of the fame folution. Two filver wires, previoufly 

 bent, were introduced a little way beyond its mouth, and then conne£led with the 

 machine in the way formerly defcribed. A very rapid produ£tion of gas twok place from 

 both wires, and a few black flocks were perceived floating in the fluid : when a fufficient 



quantity 



