Intelligence and Miscellaneous Articles. 159 



the tube very slowl)', the issuing gas, when inhaled, produces a 

 painful burning sensation in the lungs and causes violent coughing, 

 which persists for a considerable time. 



When oxygen is used, it is found that the electrodes must be se- 

 parated to a much greater distance than is necessary for air, otherwise 

 sparks pass and destroy a large proportion of the ozone already 

 formed. With air, the direct spark in the apparatus could not be 

 made to pass over an interval of more than 7 centims. ; but in oxygen 

 they did not cease until the poles were separated about 1 1*5 centims. 

 When the tube was filled with air and the poles were 7 or 8 centims. 

 apart, the discharge w^as of the silent kind ; but on admitting oxygen 

 it immediately took the form of direct sparks. 



The quantity of the solution used in these experiments was much 

 greater than would be needed in order to exhibit the characteristic 

 reactions of ozone to an audience of moderate size. One half or 

 one third of the amount would be quite sufficient ; and the time re- 

 quired for the reaction would be proportionally shorter. The great 

 quantity of the ozone, as well as the ease and rapidity with which it 

 is produced, render the apparatus especially serviceable for use in 

 the lecture-room. — Silliman's American Journal for July 1872. 



ON A SINGULAR APPEARANCE OF MAGNESIUM IN THE CHROMO- 

 SPHERE OF THE SUN. BY M. TACCHINI, IN A LETTER AD- 

 DRESSED TO M. FAYE. 



I have just observed a phenomenon which is altogether new in the 

 series of my observations. I had already, from the 6th of May, 

 discovered in the sun regions remarkable by the presence of mag- 

 nesium — very extensive regions, i.e. comprising arcs of 12-16is°, 

 whilst preceding observations give arcs of only _66° at the most. 



At the meeting of our Societe des Sciences on the 18th of May, 

 I presented a drawing of the entire margin, executed May 6, with 

 indications of the position of the magnesium, and added some special 

 considerations on the observations of the following days. Although 

 the extent of the magnesium showed itself always considerable, I 

 noticed that the longest and most characteristic streaks were found 

 on the western limb, as I had proved also, for the preceding obser- 

 vations, in the Bulletin cle V Observatoire, 1871, No. 9. This pre- 

 dilection, as it were, for the western limb was difficult to account 

 for ; consequently it was of interest to continue the study of the 

 magnesium-lines all round the margin ; and this I am doing every 

 morning w^hen the atmosphere is clear and calm. 



At last, on the 1 8th of June, I was able to verify the presence of 

 magnesium in every part of the solar margin — that is to say, that 

 the whole chromosphere was invaded by vapours of that metal. To 

 this general ebullition (which accords so well with your theory) 

 corresponded an absence of protuberances, which seems to me very 

 natural ; on the contrary, the flames of the chromosphere were very 

 pronounced and brilliant. I seemed to be witnessing the renewal of 

 the surface of our grand source of hght. 



The more pronounced and brilliant the flames, the brighter and 



