60 



The first experiments were made with tin, small plates, or arcs, of 

 which were made to alternate with acid and water. About twenty 

 sets of these produce a galvanic battery, in which the wire from the 

 oxidating surface of the plates evolved hydrogen, and that from the 

 non-oxidating surface (when of silver) deposited oxide. The second 

 series consisted of plates, or arcs, of silver, copper, or lead, placed 

 alternately between cloths steeped in water, and in solution of sul- 

 phuret of potash. The effects of this combination were much more 

 perceptible than those of the preceding. And a still more powerful 

 battery was obtained by using metallic substances oxidable in acids, 

 and capable of acting on solutions of sulphurets, and connecting them 

 with oxidating fluids, and solutions of sulphurets of potash, in such 

 a manner that the opposite sides of every plate may undergo diffe- 

 rent chemical changes. How this is to be effected is here explained 

 at length, and an apparatus, contrived by Count Rumford, is lastly 

 mentioned, for facilitating and giving permanency to the alternate 

 succession of the different substances, so as to prevent, particularly 

 in the fluids, the interference with each other, which would materi- 

 ally affect the results.; 



A Continuation of the Experiments and Observations on the Light 

 which is spontaneously emitted from various Bodies* ; with some Ex- 

 periments and Observations on Solar Light, when imbibed by Can- 

 ton's Phosphorus. By Nathaniel Hulme, M.D. F.R.S. and A.S. 

 Read June 18, 1801. [Phil. Trans. 1801, p. 403.] 



A short description is here premised of an apparatus for exposing 

 luminous bodies to different kinds of air, which, in addition to the 

 well-known glass phial or tube inverted in water, consists in a small 

 stand, to the top of which the luminous substance is fixed, and thus 

 inserted into the inverted phial, into which the species of air to be 

 employed is previously let up to the quantity of about eight ounces. 



With these instruments a copious set of experiments has been 

 made, of which the following are the principal results. 



In common or atmospherical air, all the objects which abound with 

 spontaneous light in a latent state, such as herrings, mackerel, &c., 

 do not emit it when deprived of life, except from such parts as have 

 been some time in contact with the air. Nor does the blast of a pair 

 of bellows increase this species of light, as it does that which pro- 

 ceeds from combustion. 



Oxygen gas does not act upon this kind of light so as to render it 

 much more vivid than atmospherical ah*. And as to azotic gas, 

 which is incapable of supporting light from combustion, it is remark- 

 able that it should be so favourable to the spontaneous light emitted 

 from certain fishes, as to preserve its existence and brilliancy when 

 immersed in it, while it prevents the flesh of herrings and mackerel 

 from becoming luminous, and extinguishes the light proceeding from 

 rotten wood. 



* See Phil. Trans, for 1800, p. 161, 



