Mr. Ainger on the Illumination of Theatres. 49 



small a part of the light on the stage is derived from the foot- 

 lamps. Whenever the performer is behind the line A A on 

 the plan, he is lighted principally from the lamps which are 

 numerous and powerful immediately behind the proscenium, 

 at the points A A ; from these also, and from similar lights 

 concealed behind the side-scenes, the scenery obtains nearly 

 all its light, receiving so little assistance from the foot-lamps, 

 that I have the authority of one of the most eminent scene- 

 painters for saying, that if sufficient light can be obtained for 

 the performers, there would be no difficulty in regard to the 

 scenery. I have given all the reasons which occur to me for 

 thinking that it would be sufficient in quantity ; and its average 

 direction is indicated by the sword in the hand of the figure 

 drawn on the section. 



I have, therefore, no doubt that there would be very little 

 difficulty in realizing the whole of the plan ; and that, if real- 

 ized, the result would be to add much to the comfort, conve- 

 nience, and splendour of theatres to give infinitely greater 

 effect to the scene and to do justice to the features and ex- 

 pression of the performers. 



[See Note at the end of the Miscellanea.] 



ON THE RED SOLUTIONS OF MANGANESE, 



BY THOMAS J. PEARSALL, 



Chemical Assistant in the Royal Institution. 



HP HE crimson solutions obtained by the action of certain 

 acids upon oxides of manganese, possess some remarkable 

 properties, which have received only partial and unsatisfactory 

 explanations. It has been hitherto supposed that an oxide of 

 manganese existed, which was capable of dissolving in acids, 

 to produce pink or deep red coloured solutions, but the 

 precise state of oxidizement has not been agreed upon. The 

 red oxide, deutoxide, and peroxide have each been selected 

 as the one present*. 



In consequence of experiments which I have made to dis- 



Gay Lussac, Annales de Chiraie, i. p. 39. Berzelius, Traiie de Chimie iii 

 p. '298. Thenard, Traite de Chimie, 5th edit., iii. p. 184. Turner's Elements of 

 Chemistry, 2nd edit., pp. 471, 475. Thomson's First Principles of Chemistry. 



VOL. II. AUG. 1831. E 



