Intelligence and Miscellaneous Articles. 77 



may perhaps lead to a further investigation of the subject. I ought 

 perhaps to remark that in those specimens where the circumstance 

 above mentioned has taken place, carbonate of lime is, in all proba- 

 bility, the principal lapidifying agent. 



I have observed something similar, but not so distinctly shown, in 

 wood that has become completely silicitied. 



I remain, Gentlemen, yours, &c. 



Guy's Hospital, March 23, 1835. Edward Charlesworth. 



phenomenon resembling the mirage, seen in the 

 regent's park. 

 To the Editors of the Philosophical Magazine and Journal. 

 Gentlemkn, 



Perhaps the following occurrence is not so frequently observed in 

 England as to make a notice of it unworthy of publication in your 

 Magazine. 



Upon walking along the newly constructed promenade in the Re- 

 gent's Park, ascending the first hill from the Zoological Gardens, as 

 soon as the eye is raised a little above the level of the highest part, 

 the appearance of a sheet of water crossing the path between this hill 

 and the next elevation is visible, with the reversed images of distant 

 persons and objects reflected in it. Of course this phenomenon is 

 most conspicuous on a very warm day : it reminds the spectator of 

 similar occurrences in sandy deserts. 



Camden Town, June 23, 1835. I am, &c. J. De C. Sowerby. 



experiments to ascertain the existence of lead in 

 the atmosphere of a white-lead manufactory. by 

 mr. arthur dunn. 



To the Editors of the Philosophical Magazine and Journal of Science. 

 Gentlemen, 



Having witnessed at my manufactory the frightful effects of white- 

 lead on the workmen employed, I was anxious to determine if it was 

 possible for lead to exist in the atmosphere, and through that medium 

 be absorbed into the system by the action of the lungs. For this 

 purpose I made the following experiment, which certainly is impor- 

 tant to the manufacturer, as it points out a serious evil to be guarded 

 against. I shall now merely confine myself to the results obtained, 

 and leave to some of your more scientific friends any theoretical rea- 

 soning or practical hints the experiment may suggest, provided you 

 consider it worthy to occupy a space in your valuable Magazine, and 

 remain, Gentlemen, yours, &c. 



Chemical Works City . Road, Arthur Dunn. 



January 19th, 1835. 



An evaporating dish, containing about 28 lbs. of moist carbonate of 

 lead, was placed in a sand-bath, and heated to about the same tem- 

 perature as the drying stove commonly used, never exceeding 150° 

 Fahr. : over this was fixed, at the distance of from eight to twelve 



