1815.] in the Physical Sciences. 29 



tiian carbonic acid, common air, and water. The experiment 

 would deserve a careful repelition. If correct, how much light 

 would it not throw on the nature of acetic acid ? 



7. Arsenioits Acid. — Various and discordant statements have been 

 published respecting the solubility of white arsenic in water. The 

 result of Klaproth's trials was lately published in the Annals of 

 Philosofjfii/, Since that time a still more elaborate set of experi- 

 ments on the same subject has been published by Bucholz. His 

 results agree more nearly with those of Klaproth than with any 

 other ; thoup;h there are several anomalies in his experiments which 

 are sufficiently puzzling. 1 have long been of opinion that the 

 white oxide of arsenic exists in two states ; namely, in the state of 

 pure oxide, and in the state of hydrate of arsenic. When first 

 prepared, it is transparent and colourless, like glass ; but it gra- 

 duiiliy becomes white and opake, and puts on the appearance of 

 enamel. The glass I conceive to be the pure oxide of arsenic ; the 

 enamel, to be a hydrate. Now if this opinion be well founded, we 

 may expect to find a difference in the solubility of white arsenic in 

 these two states^ I think it probable that several of the anom;ilies 

 are owing to chemists not having hitherto attended to this difference 

 of state. 



VII. Salts. 



This is always one of the most prolific departments of chemistry, 

 on account of the great number of salts, and the importance of 

 being acquainted with their properties ; but this historical sketch 

 has already swelled so much, that 1 shall omit all the salts treated 

 of in the Annals of' Philosophy during the last year. 



1. Calomel. — Mr. Jewel's improvement in the manufacture of 

 calomel, by making it pass in the state of vapour into water, is 

 known, I presume, to most of my readers ; having been made 

 known to the public by Mr Luke Howard, in whose manufactory 

 it took place, about Ibur years ago. 



'2. Oxalates. — Vogel, of iiayreuth, has published nvo very elabo- 

 rate, and 1 conceive very accurate, sets of experiments on the 

 analysis of several of the oxalates. I cannot attempt in this place 

 to do more tiian give a bare table of his results. What makes these 

 exjjeriments more valuable, is their agreement with the views of 

 Btrzelius respecting the composition of salts; though when Vogel 

 made his experiments (at least the set of them first pulilishedi.) it 

 does not ajjpear that he was acquainted with Berzelius' opinions on 

 the sul)ject. 



A hun(h''d parts of oxalic acid require for saturation a quantity 

 of jjase wiiich contains 21*2 parts of oxygen ; or in other words, in 

 the neutral oxalates the acid contains three times as much oxygen 

 as the base. 



VV hen binoxalate of potash is poured upon carbonate of copper, 

 a solution takes place, and two salts are formed, distinguished from 



