On ike EmpIoi/?ne?2t of Carhon in Voltaic Combinations. 35 



72. Palm Squirrel, adult, [Sciurus palmarum). Dry; most 

 commonly l-3692nd, extreme sizes l-4800th and l-3000th. 

 In their own serum or in urine tliey seemed contracted, the 

 corpuscles often cup-shaped, bent, or shrunk, ranging from 

 l-4S00th to 1 -4000th. Blood from a prick of the tail. 



73. Furnier's Capromys, adult, [Capromys Furnieri). Dry; 

 common diameters l-3530th and l-3429th. Extreme sizes 

 l-4000th and l-3000th. Blood from a prick of the ear. 



74'- Bandicoot Rat, adult, {Mus gigantens). Corpuscles in 

 their own serum very irregular in size, most frequently 

 l-4000th of an inch, and many from l-5333rd to l-3200th. 

 There was evidently considerable shrinking of the corpuscles 

 while under examination, as observed in several trials. In 

 dried specimens the disks were generally from l-4000th to 

 l-3600th. Extreme sizes l-4800th and l-3200th. Blood from 

 a prick of the tail. 



75. Hoary Marmot or Whistler, an old animal, [Arctomys 

 pruinosa). Dry; most commonly l-3600th. Extreme sizes 

 l-4000th and' l-3000th. Blood from a prick of the upper 

 lip. 

 Regent's Pai-k Barracks, Nov. 22, 1839. 



V. On tlie Employment of Carhon in Voltaic Combinations. 

 By Mr. John Thoimas Cooper, Lecturer on Chemistry^ 

 S)C. Sj-c. 



To Richard Phillips, Esq., F.R.S., S$c. 

 Dear Sir, 



TT occurred to me on reflecting upon the use of the platinum 

 •"■ as employed by Mr. Grove in the construction of his 

 very energetic voltaic combination*, as it was only to conduct 

 the electricity from the decomposing nitric acid, that any 

 cheaper substance which conducted electricity, and upon 

 which nitric acid had no action, might be employed with equal 

 advantage, and probably supply the place of the more ex- 

 pensive material. With these views I was induced to make 

 trial o{ charcoal, and the other forms of carbon, viz. plumbago, 

 and a peculiar kind of carbon which is frequently met with as 

 an incrustation in the retorts in which coal is decomposed for 

 the purpose of gas lighting; and was gratified on making the 

 experiments in finding my anticipations fully realized. In 

 order to show the comparative value of each of the substances, 

 I here subjoin the results of some of the experiments made 

 with acids of the same strength, and with amalgamated zinc 

 cylmders, each presenting to the action of the dilute sulphuric 



[* See Lond. & Edinb. Phil. Mag., Oct. 1839, vol. xv. p. S87.] 

 D2 



