314. Scientific Intelligence. [Oct. 



V. Ulmin. 



Professor'Berzelius informs me, in a letter which I lately 

 received from him, that ulmin is a vegetable substance, not 

 confined to the genus ulmus, but that it forms a constituent part 

 of the barks of almost all trees. He found it in the bark of the 

 cinchona officinalis {Jesuit's bark), and in that of the pini/s syl- 

 vestris (Scotch Jir). It cannot be discovered by the usual mode 

 of analysing bark ; because, when the bark is digested in hot 

 water, the ulmin combines with the tannin of the bark, and can 

 be no longer recognised as a peculiar substance. If we begin 

 the analysis by digesting the bark in alcohol, and afterwards in 

 cold water, the ulmin remains undissolved, and may be after- 

 wards obtained by means of hot water, especially if that water 

 holds a little alkaline carbonate in solution. The properties 

 which I found the substance thus obtained to possess agree nearly 

 with those which you assign to ulmin. " If," says Dr. Berze- 

 lius, " you think this subject of any importance, I have no 

 doubt that my friend Dr. Young will communicate to you the 

 details of my comparative analyses of these two barks, which 

 you will probably find interesting in other respects besides in 

 those particulars which relate to ulmin." 



VI. Oxides of Gold. 



Professor Berzelius has favoured me with the following ob- 

 servations on the account of the oxides of gold which appeared 

 in the second Number of the Annals of Philosophy : — " In your 

 account of the oxides of gold you have done me the honour to 

 quote my Manual of Chemistry on the subject. Though I am 

 much flattered by the circumstance, I must take the liberty to 

 observe, that the numbers which you have quoted as mine have 

 been inaccurately quoted. In my Manual I have said that 100 

 parts of gold combine with 4 and with 12 of oxygen, omitting 

 the fractions. In Davy's Chemistry the result of the same 

 analyses is added as an appendix, but by an error of the press 

 11 *026 has been printed instead of 4*026. — You have given the 

 description of the oxide of gold from Vauquelin. Yet M. 

 Oberkampf, whose dissertation you likewise quote, has proved 

 by decisive experiments that what Vauquelin considered as an 

 oxide of gold is in fact a submuriate. I have verified this as- 

 sertion of Oberkampf. The oxide of gold is blackish brown, 

 and is obtained by dropping muriate of gold into a solution of 

 caustic potash in water. — Towards the end of that article, you 

 draw, as a consequence from the experiments of Oberkampf, 

 that the observation which I have made respecting the ratio of 

 the sulphur in the sulphuret, and the oxygen of the oxide of 

 the same metal, may be rejected as inaccurate in consequence 

 of the want of correspondence between my experiments and his. 

 A small mistake in the translation, it appears, here occasioned 



