1814.] Mr. Scheele. IG9 



compound of lime and a peculiar acid, to which the name of 

 tungstic acid was given. The Elhuyarts afterwards showed that 

 Scheele's tungstic acid was a triple salt which had been formed 

 during his experiments, and that the true tungstic acid is an inso- 

 luble tasteless powder. They showed also that it is a metallic 

 oxide, and even succeeded in reducing it to the metallic state. 



15). In 17i">~ he published his observations on ether, containing 

 the result of a prodigious number of experiments, made partly with 

 the view of ascertaining the various acids and other substances 

 capable ot converting alcohol into ether, and partly in order to 

 determine the natuie of the change produced upon alcohol when it 

 is converted into ether. It would Le impossible to state all the facts 

 contained in this curious piper, without transcribing almost the 

 whole of it. The general result was, that ether is dephlogistieated 

 al :ohol. This gave origin to .he French theory, which prevailed 

 for some time, that ether is alcohol united to oxygen. But as facts 

 are utterly inconsistent with this opinion, it has been for some 

 years altogether discarded. 



20. In the same year he published a method of preserving 

 vinegar (obtained from grain) for a long time without undergoing 

 decomposition. The method was to expose it to a boiling heat, 

 and then to cork it up. 



21. Scheele's two dissertations on Prussian blue were published 

 in the Memoirs of the Stockholm Academy for 1782 and 1 783. 

 They place in a very conspicuous point of view the patient industry 

 of the author, his invincible perseverance, uncommon sagacity, 

 and unrivalled skill in the knowledge of the chemical action of 

 bodies on each other. Though Prussian blue had been known for 

 70 years, and had been subjected to many experiments by chemists 

 of acknowledged abilities, nothing was known respecting its con- 

 stituents. Scheele ascertained its composition, separated the 

 prosaic acid, ascertained its properties, determined its composition, 

 and showed in what way it acts upon other bodies Very little has 

 been since added to these admirable dissertations, if we except the 

 important discoveries of Mr. Por.rett, which are not yet published. 



22. In 17' s l be published an account of a sweet-tasted matter 

 which separates from oils when thev arc digested with litharge. 

 This substance has been since known by the name of the siveet 

 principle of oils. 



2.1. The same year he gave the method of obtaining citric acid 

 in a state of purity ; which had not been hitherto done. Lemon 

 juice was saturated with chalk, the precipitate washed, and mixed 

 with as much diluted sulphuric acid as is just sufficient to saturate, 

 the lime employed. The liijuid is then filtered, concentrated, and 



t by to crystallize. 



-i. Ill- next discovery was, that rhubarb contains a considerable 

 quantity of oxalate of lime. He separated it by digesting powdered 

 rhubarb in water, and pouring off the liquid, which carried off the 

 vegetable matter partly in solution, partly suspended, while the 



