lOG Chronicles of Science. [Jan., 



acid is obtained by heating in a water-batli a tube supplied with a 

 cork and dehvery tube, and containing a mixture of 9 eqs. of oxalic 

 acid and 1 eq. of chlorate of potash. 



Professor Wohler has also pubhshed a good method of separating 

 phosphoric acid from bases. It consists in dissolving the substance 

 to be analyzed in a small quantity of nitric acid, and adding to the 

 solution, first nitrate of silver, then carbonate of silver, and well 

 shaking. All the phosphoric acid then combines with the oxide of 

 silver and is precipitated, whilst the bases remain in solution and 

 may be freed from the excess of silver by means of hydrochloric 

 acid. 



The element phosphorus has been applied by W. Schmid as a 

 re-agent for metals. When a solution of crystallized phosphorus 

 in bisulphide of carbon is shaken with water, a perfectly white pre- 

 cipitate is formed. The presence of traces of metals causes the 

 precipitate to assume various colours. Thus solutions of copper 

 are precipitated brown ; those of silver, black ; of mercury (oxide), 

 yellowish brown ; of gold, violet. The filtrates contain generally 

 sub-oxides. 



In an examination into the action of iodine on the hydrogen 

 compounds of antimony and arsenic, M. Husson has discovered a 

 reaction which may furnish a useful application in toxicological 

 researches. He finds that aatimoniuretted hydrogen and arseni- 

 uretted hydrogen form iodide of antimony and iodide of arsenic 

 when the two gases are made to pass over iodine. A tube con- 

 taining a small piece of iodine being joined to the Marsh's apparatus, 

 gentle heat is apphed to volatilize the iodine, which, upon condensa- 

 tion, lines the tube. Then, while the tube is still slightly warm, the 

 gas is allowed to pass. If this contains arseniuretted hydrogen, 

 the iodine will bo bordered by a yellow line formed of little straw- 

 like masses, having much analogy with iodoform ; tbe iodine (hsap- 

 pears completely. With antimoniuretted hydrogen the reaction is 

 less manifest ; all the iodine coDects, forming a deep ring, orange- 

 tinted on the one side, and brown on the other. But the action of 

 heat enables these two iodides to bo distinguished thus : — The yellow 

 iodide of arsenic is transformed, one part into red iodide with dis- 

 engagement of iodine, the other volatilizes in the state of yellow 

 vapours, which are received on unsized paper ; the same phenomenon 

 is produced under the influence of an excess of arseniuretted hydro- 

 gen, whence M. Husson is inclined to conclude that a periodide of 

 arsenic is first produced. Iodide of antimony, on the other hand, 

 evolves red vapours, and leaves a little reduced antimony. 



Dr. T. Werner recommends the following process to detect the 

 presence of atmospheric air in coal gas : — Ten parts by weight of 



