222 Scientific Intelligence. 



be raised so that it barely enters the hollow ball at the top, r 

 escape takes place from it, and the machine will gi%'e its fu 

 length of spark. By varying the position between these two 



limits, any required length of spark or amount of charge 

 -Leyden jar - ' 



itei-posed Leyden jar can be obtained.- 



13. Eeport to the Philosophical Society of Glasgow on the Pro- 

 duction of Nitric acid from the free Nitrogen of the air. Part I. 

 By E. M. Dixon. 18 pp. 8vo. Glasgow, 1875.— The author first 

 discusses the researches connected with ozone made by Schonbein, 

 Marignac, De La Rive, Baumert, Prof. Andrews of Belfast, and 

 others, and states, as the accepted conclusion, that ozone is the 

 only allotropic form of oxygen, in other words that antozone has 

 no existence. The report then considers the production of nitric 

 acid through the agency of ozone ; four alleged methods of which 

 are mentioned, viz. : (1) by contact of nitrogen or the atmosphere 

 with bodies undergoing oxidation ; (2) during electrical discharges 

 in the air; (3) the combining of ozone with nitrogen in the pres- 

 ence of water; (4) through the evaporation and condensation of 

 water in the air. The consideration of nitrification by the fipt 

 method' is pronounced to be as yet doubtful, but the consideration 

 of it is deferred to the second part of the report. With regard to 

 the second and third methods, it states that there is clear proof 

 of the fact that the electric spark is capable of effecting the com- 

 bination of oxygen and nitrogen in a dry mixture of these gases ; 

 but that there is little or no doubt that nitiification does not occur 

 in nature from the action of ozone upon the nitrogen of the air ; 

 and that the production of peroxide of hydrogen in nature, as 

 shown by Engler, Nasse, Carius, Schone, must be ascribed to some 

 other cause than the action of ozone upon either aqueous vapor 

 alone, or upon it and nitrogen together. 



Upon the fourth method, the report remarks as follows : " In 

 1862 Schonbein announced the fact that, if water is partially 

 evaporated in the air, the residue contains nitrite of ammonia, and 

 that the same salt is to be found in the water formed by the con- 

 densation of vapor in air. Of these facts there is no doubt. 

 Schonbein, however, without ascertaining whether the salt in 

 question did not exist ready formed in the air employed in his 

 experiments, rushed to the conclusion that it must have been 

 formed during these experiments, by the combination of free 

 nitrogen with water. Obvious as the precaution indicated now 

 seems to be, it must also be said that it does not appear to have 

 occurred at the same time to any one else ; and some, while ac- 

 cepting Schonbein's explanation of the production of nitrite of 

 ammonia from free nitrogen and water, even thought to contest 

 his claim to all the merit of having discovered so remarkable a 

 property in free nitrogen. The following quotation from a re- 

 cently published volume, by Dr. T. Sterry Hunt, entitled Chem- 

 ical and Geological Essays, will show that he still claims a con- 

 siderable amount of credit for having predicted, on theoretical 



