748 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



A New Actinic Light. 

 In England artificial light is often used for producing photo- 

 graphic pictures. Mr. Sayres has invented a new compound hav- 

 ino" high actinic power. It consists of twenty-four grammes of nitrate 

 of potash, well powdered and dried; seven grammes of flour of 

 sulphur, seven grammes of red sulphuret of arsenic. These ingre- 

 dients arc thoroughly ground together. Four hundred grammes 

 in burning will make a light lasting one minute at a cost of about 

 three cents; while light from the combustion of magnesium wire, 

 for the same length of time, costs about twenty-five cents. 



The Talloav Tree. 

 This tree, indigenous to China, has recently been introduced 

 into India, and there are now tens of thousands of trees on the 

 Government plantations. The tree fruits abundantly both in the 

 Dhoons and on the plains, and grows with great rapidity. Mauy 

 trees raised from seeds planted eight years ago are now at least 

 two feet in diameter. Dr. Jameson prepared from the seeds of 

 the fruit one hundred pounds of tallow, half of which has been 

 o-iven to the Punjab railwa^^ in order to to have its qualities as a 

 lubricant of axles tested. This tallow burns with a clear, inodor- 

 ous flame, and without smoke. The leaves of the tree are valua- 

 ble as a dye, and the timber, being white and close-grained, is 

 well fitted for printing blocks. 



Color of Deposited Silver. 

 M. Carey Lea, of Philadelphia, noticed a curious fact in the 

 course of a photographic experiment. A plate was covered with 

 a considerable thickness of ammonia-nitrate solution, to which was 

 added a dilute solution of Rochelle salt. The plate was then 

 placed in the sunlight and left for some time. Reduction took 

 place, and the evaporation, which went on simultaneously, had 

 exhausted over about one-half of the plate, when it was removed 

 from the sunlight and carefully washed. All that part of the 

 metallic silver on which the solution had been suffered to dry in 

 the sun was pure steel gray, while that which was removed, still 

 wet, had a strong reddish bloom. The contrast between the two 

 was remarkable. It was, moreover, quite permanent, and evi- 

 dently depended upon some diflerence of molecular arrangement. 



Egyptian Brick. 

 Prof. Unger, in a paper read before the Academy of Vienna, 

 gave the results of his examination of brick from the pyramid of 



