On a Leather-like Substance composed of Infusoria. Q5 



discrepancy of the results, that the method is not susceptible 

 of sufficient accuracy for the present purpose. 



In my own analyses of naphthaline, the carbon and hydrogen 

 bear such a relation to each other, that assuming its constitu- 

 tion to be C3 H,, the number for carbon, according to each 

 experiment, will be 



(1) (2) (3) 



6-026 6-059 6-096 



The mean of which gives 6-06. 



It appears to me therefore on the whole, that the analysis 

 of certain hydrocarbons offers a surer mode of settling the 

 question at issue than a comparison of the densities of the two 

 gases ; and of all known substances of this kind, none seems 

 better adapted to the purpose than naphthaline, inasmuch as 

 its very peculiar physical and chemical character renders it a 

 matter of no difficulty to obtain it in a state of complete pu- 

 rity. It is obvious that a considerable number of analyses, 

 made under diffiarent circumstances, and with various samples 

 of the substance, will be necessary in order to obtain an ap- 

 proximation sufficiently good to be relied on. 



In the experiments above related the usual means were 

 adopted to guard against the besetting error of organic analy- 

 sis — the tendency of the oxide of copper to attract moisture 

 from the air, and so render the hydrogen estimation worthless. 

 I am indebted to the kindness of Mr. Everitt for the use of 

 the instruments employed, and take this opportunity of ex- 

 pressing my gratitude. 



I remain yours most respectfully, 



Geo. Fownes. 

 6, Coventry Street, April 5, 1839. 



XIII. — On a Leather-like Substance found formed upon a 

 Meadow. By Charles Kersten, Prof, of Chemistry in 

 Freiberg, Saxony, and Prof. Ehrenberg. of Berlin*. 



INCLOSED I send you an interesting vegetable production, 

 having a deceptive resemblance to white dressed glove- 

 leather, and which was found by M. Lindner on a meadow 

 above the wire-factory at Schwartzenberg in the Erzgebirge. 

 A green slimy substance grew on the surface of the stag- 

 nant waters in the meadow, which, the water being sIom ly let 

 off, deposited itself on the grass, dried, became quite colour- 

 less, and might then be removed in large pieces. The outside 



• We are indebted for this communication, and for a specimen of the sub- 

 stance described, to tlie kind attention of Prof. Kersten. The original ap- 

 peared in PoggendorfF's ' Annalcn,' Part I. 1839. — R. T. 



Phil. Mag. S. 3. Vol. 15. No. 93. July 1839. F 



