68 Notes and Memoranda. 



quently establishes a communication between the colonial and the indiyidual 

 nerve systems." 



Test for Oxygenized Water. — M. Schonbein finds iodized starch, to wbich 

 has been added a little acetate of lead, and a little acetic or nitric acid, the most 

 sensitive test for oxygenized water. Peroxide of lead is formed, and this substance 

 evolves the blue colour in the iodized starch, especially in the presence of free 

 acids. Water containing a three millionth part of oxygenized water gives a sen- 

 sible blue colour with this reagent. — Archives des Sciences. 



Production of Nitrate or Ammonia by Aie and Water. — M. Schonbein 

 has shown that nitrate of ammonia is formed at the expense of air and water, 

 during the slow combination of phosphorus ; he has likewise proved that this salt 

 is present in metoric waters, and has thence concluded that its formation must be 

 due to a very general cause. He now announces that this cause is found in the 

 simple fact of the volatilization of water in free air, and he cites many experiments 

 which confirm this belief. The process which succeeds the best is to cause water 

 to fall drop by drop in a metallic vessel heated above lOO 3 C, without, however, 

 reaching the point at which the liquid passes into the spheroidal state. By hold- 

 ing a cold flask above the vapours which are produced, he condenses enough water 

 to recognize the presence of nitric acid and ammonia. M. Schonbein has remarked 

 that the quantity of nitrate of ammonia condensed with the vapour of the water 

 is very variable, sometimes almost nil, and he is disposed, in the absence of any 

 positive determination, to attribute these variations to changes of temperature. 

 It is not, however, necessary that the water should boil, as the salt is produced 

 during all evaporation, and its presence may be shown in the water that remains 

 after a portion has been evaporated. A sheet of filtering paper dipped in pure 

 water, and dried in the air, becomes impregnated with sufficient nitrate of 

 ammonia to be distinguished in the water with which the paper is washed, and it 

 can be discovered in linen that has been washed and hung up to dry. In all 

 these cases the production of nitric acid may be rendered more evident by adding 

 to the water which is evaporated a little potash, to fix the acid. Wet sand dried 

 in the air becomes impregnated with nitrate of ammonia." The editor of the 

 Archives des Sciences, from which the above account is taken, regrets that M. 

 Schonbein did not ascertain whether the salt was produced by evaporation of 

 water in a limited quantity of air, as, if so, the objection to the conclusiveness of 

 his investigations, arising from the possible wide diffusion of the salt, and its mere 

 condensation, under the circumstances he mentions, might be removed. 



Shell o? the Cuttle Fish. — In our third number we called the attention of 

 microscopists to the beautiful character of the shell of the cuttle fish as a polarized 

 object, and we indicated the way in which its structure should be examined. We 

 have since received from Mr. Baker of Holborn an exquisitely prepared slide, con- 

 taining a thin section of the shell, showing the floors and the corrugated sheets of 

 crystalline carbonate of lime by which they are supported, and separated, so as to 

 make the shell at once firm and light. 



New Polariscope Object. — Pleasing results may be obtained with the 

 Platinocyanide of ammonia, a very striking salt, exhibiting the phenomenon of 

 dichroism. It is red in one view, and green in another. With the polariscope the 

 beauty depends on the condition of the crystals. A few experiments will show 

 what is required. 



The Comet of 1861. — We learn from Cosmos that the astronomers at Pul- 

 kova saw this object as late as the 1st of May, after which the nights became too 

 bright to permit their following its course. Towards the end of May, the light 

 in the sky was so strong at midnight that they were able to read in a room facing 

 the north. 



Markings on Diatoms. — On this interminable controversy the President of 

 the Hull Microphilosophical Society, George Norman, Esq., remarks that, " after 

 duly considering the cellular or areolar theory, that such structures, though at 

 first -view appearing cellular, yet after more careful study and observation, are 

 evidently granular, the granules being in some species isolated and round, in others 

 more closely crowded and compressed, causing an appearance of hexagonal cel- 

 lulation." 



