544: AS3JUA1, OF SCIENTIFIC DISCOVERY. 



10-8 mm. per litre (or 0'66 gr. per gall.) of ammonia, and traces of nitric 

 acid. This experiment shows that the atmosphere of our cities is more 

 strongly charged with ammonia, than that of the countiy. 



OX THE USE OF BICHROMATE OF POTASH FOE PRESERVATIVE 



SOLUTIONS. 



A correspondent of the Medical Times and Gazette says : This salt, in 

 the proportion of about four grains to an ounce of water, constitutes a solu- 

 tion quite equal to alcohol in its antiseptic powers, and which costs only about 

 twopence a gallon. It will deprive a specimen already partially decomposed, 

 of all odor, and preserve it for any length of time. As, instead of hardening, 

 it a little softens tissues immersed in it, it has a great advantage over both 

 alcohol and Goadby's solution, for all objects which arc intended to be re- 

 examined, especially if the microscope is to be used. Preparations long kept 

 in it become of a light olive green color externally, but retain most perfectly 

 their natural appearance at a little depth from the surface. The change of 

 color in the case of red structures, such as muscle, may be prevented by the 

 addition of a little nitrate of potash. In the same way, if it is desired, the 

 softening may be prevented by 'the use of alum. Unless in combination with 

 both the two last-named ingredients, it is scarcely adapted for a permanent 

 solution. The great advantage over all others, is, in respect to specimens 

 intended to be kept for limited periods, either for private dissection or for 

 exhibition. These intended for the microscope are far less spoiled by it than 

 by any other which I am acquainted with. The only odor which it gives to 

 specimens is a very peculiar one, resembling that of new kid gloves. The 

 cheapness and efficiency of this salt Yfill, I think, make it quite a boon to 

 pathologists. 



TTATERS OF ARTESIAN WELLS. 



On examining the waters of the Artesian well of Grenclle, with reference 

 to the gases present, M. Peligot has ascertained that they contain not the 

 least trace of air. Subterranean waters ought therefore to be ccratcd before 

 being used as an aliment, and accordingly they are about to construct at 

 Grenclle a species of tower, from the top of which the water will descend in 

 innumerable threads, so as to present as much surface as possible to the air. 



RESEARCHES ON THE PRODUCTION OF OZONE. 



M. do Luca, in a communication to the French Academy, states, that, 

 having found that by passing humid ozonized air over potassium and pure 

 potassa, he obtained nitrate of potassa, which could be separated from t!:c 

 alkaline solutions by means of crystallization ; he desired to ascertain 

 whether the oxygen disengaged from the leaves of plants by the action of 

 solar light, or the air which surrounds plants during vegetation, presented the 

 characters of ozone. As the result of his researches, M. Luca says, that he 

 has not obtained results which agree in many trials and experiments made 

 with leaves, whether detached or not detached from several plants, or with 



