1813.] On Ulmin. 23 



process. Some further inquiries are evidently jequishe on this 

 head, before we can satisfactorily explain the phenornena. 



One valuable object, I conceive, obtained by the preceding 

 experiments, is the acquisition of a more complete and easy test 

 of the quantity of oxymuriatic acid in any solution, than we 

 have had hitherto, in green sulphate of iron. It requires little- 

 or no skill in the application, and can always be commanded of 

 the same strength j whereas coloured solutions are not easily 

 obtained of the same strength, and are liable to decay. Expe- 

 riments on the occidation of metals, and on occidation in general, 

 will be conducted with greater precision, having a reference to 

 the exact quantity of oxygen with which bodies sublime, when 

 that combination is effected by means of oxymuriatic acid. The 

 quantity of red and green sulphates of iron in given solutions 

 will be readily determined, and the green converted into the red 

 at pleasure. But it is needless to enlarge on the uses and appli- 

 cation of the oxymuriates, as they will easily be suggested to the 

 practical chemist when the nature of these compounds become 

 more perfectly known. 



Article III. 



071 Ulmin, By Thomas Thomson, M.D. F.R.S. 



In the year 179/ Mr, Vauquelin published a paper, entitled 

 Observations sur une maladie des arhres qui attaque specialement 

 rOrme, et qui est analogue a tin ulcere.^ In this paper he de- 

 scribed two kinds of morbid matter which flowed from the 

 common elm ; the one whitish, and nearly as limpid as water; 

 the other dark brown, of greater consistency, and covering the 

 bark of the elm with a kind of varnish. The white coloured 

 sanies contained the following substances : 



Vegetable matter 0 605 



Carbonate of potash 0'642 



Carbonate of lime 0'05() 



Carbonate of magnesia 0-003 



1-000 



The brown substance he found a combination of potash and a 

 peculiar vegetable matter, resembling gum in several of its 

 properties, but differing in several circumstances from that 

 vegetable principle. It was soluble in water, insoluble in alcohol, 

 precipitated from its solution by acids, and when burnt yields an 

 acrid smoke, without any smell of caramel. 



No notice of these experiments was taken by any subsequent 

 writer. But in the year 1S04 Klaproth published a paper, en- 

 titled Chemische Untersiicliung eines gmnmigeii pjiaimeiisaftes 

 * Anualesde Chiuiie, yol» x\u p. S9, 

 4 



i 



