388 Intelligence afid Miscellaneous Articles.. 



1 have also stated, that the disinfecting solution may be evaporated 

 to dryness and retain bleaching power. He observes, that " notwith- 

 standing the perfect manner in which the chlorine may be separated 

 by crj-stailization and slow evaporation, yet it is certain that by quick 

 evaporation a substance apparently quite dry may be obtained which 

 yet possesses strong bleaching power." He considers that the car- 

 bonate of soda acts as a more simple substance with the chlorine : 

 when, however, excess of chlorine is passed into a solution of car- 

 bonate of soda, carbonic acid is evolved, and muriate and chlorate 

 of soda are formed, in the same manner as when caustic soda is em- 

 ployed. With respect to Dr. Granville's opinion, Mr. Faraday con- 

 cludes with the following observations. " It would seem as if I were 

 unacquainted with Dr. Granville's paper on this subject, published 

 in the last volume of this Journal, p. 37 1 , were 1 to close my remarks 

 without taking any notice of it. Unfortunately, Dr. Granville has 

 mistaken M. Labarraque's direction; and by passing chlorine to 

 * complete saturation' through the carbonate, instead of using the 

 quantities directed, has failed in obtaining Labarraque's really 

 curious and very important liquid ; to which in consequence not one 

 of his observations or experiments applies, although the latter are 

 quite correct in themselves." 



PREPARATION OF SPONGY PLATINA. 



M. Doebereiner procures the above substance by the following 

 process : — Mix muriate of platina with neutral tartrate of soda dis- 

 solved in water ; this mixture is to be heated in a glass tube (about 

 4- or 4 of an inch in diameter, and 20 to 30 inches in length) until 

 the fluid is rendered slightly turbid, and it is afterwards to be ex- 

 posed for several days to the sun's rays. The greater part of the 

 platina is separated from solution, and deposited in the state of minute 

 laminae of a grayish-black colour, on the sides of the glass. The 

 tube and its contents are to be put into a glass vessel containing 

 water, and it is to be filled with hydrogen gas. The platina deposited 

 upon the glass becomes almost immediately white and shining like 

 silver. The platina may be then readily detached from the glass. 

 During the reduction of the platina by this process, the tartaric acid 

 is partly converted into carbonic and formic acid. As the inflamma- 

 tion of the hydrogen is caused by abstracting a portion of the ca- 

 loric from the oxygen, eft'ected by the platina, the smaller the la- 

 minae of the metal are, the more readily is the incandescence pro- 

 duced. Spongy platina (for the lamps for instantaneous light) is 

 prep.ired of great power by moistening the muriate of ammonia and 

 platina with a concentrated solution of ammonia ; the paste formed 

 is to be heated to redness in an earthen or platina crucible. — Hens- 

 man's Repertoire de Cliimie, S^c. 



TEST OF NITRIC ACID. 

 Dr. Liebig proposes the following process for detecting the pre- 

 sence of nitric acid : the fluid to be examined is to be mixed with as 

 much sulphate of indigo as will give it a distinct blue colour, and 



after 



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