THE DIAPHOTE. 693 



A different mode is pursued with silver, for the reason that, when silver is alloyed 

 with copper, there is a separation to a greater or less degree between the two 

 metals in the act of gradual solidification. From the sample the weight of 1,115 

 thousandths is taken, which is dissolved in a glass bottle with nitric silver. Into 

 this solution the large pipette full of standard solution of salt is introduced, and 

 immediately a white precipitation is formed, which is the chloride of silver, and 

 and contains of the metallic silver 1,000 parts. The bottle is violently shaken by 

 a mechanical arrangement, and so continues to be shaken, until the addition of 

 salt water only shows a faint trace of chloride below the upper surface of the 

 liquid. In making the test assay a roll of silver of known absolute purity is kept 

 from year to year under the seal of the Chairman of the Commission. This is 

 opened, and 1,004 parts weighed off and submitted to the same process as em- 

 ployed with the coin. If the salt water used be of the exact standard, the solu- 

 tion in the larger pipette will precipitate 1,000 parts of silver; four measures of 

 the decimal solution will be required to precipitate the remaining four parts. The 

 assay will be finised to-day. — Philadelphia Press. 



THE DIAPHOTE. 



The Diaphote is an instrument by which you can see by telegraph. Dr. H. 

 E. Licks, of Bethlehem, Pennsylvania, has invented an instrument which he calls 

 by this name, from two Greek words, dia, through, axi&phos, light. He read a 

 paper in Reading, the other day, and exhibited his instrument. This consists ot 

 a receiving mirror, the wires, a battery, and a reproducing speculum. The re- 

 ceiving mirror is an amalgam of selenium and iodide of silver ; the reproducing 

 speculum is a compound of selenium and chromium. The wires are numerous, 

 as it is necessary to distinctness that a wire should not be required to affect but a 

 very small space. The instrument exhibited had a mirror six inches by four, 

 composed of seventy-two small plates, to each of which a wire was attached, the 

 whole being wrapped by a fine insulated covering. These wires run to a common 

 galvanic battery and thus connect with the reproducing plate. When the cir- 

 cuit is closed, the rays of light are conducted through an ordinary camera, and the 

 accompanying heat produces chemical changes in the amalgam of the mirror, 

 which, modifying the electric current, cause similar changes in'^the reproducing 

 speculum. 



In the experiments at the close of the explanatory lecture, an instrument was 

 taken to a lower room of the building and operated from there to the stage in 

 presence of the audience. Before the mirror in the lower room the committee 

 held in succession an apple, a pen knife, and a trade dollar, which were distinct 

 on the platform above. The date on the trade dollar, thrown on an enlarged 

 screen, was plainly visible, as well as the goddess of liberty. A watch was next 

 used, and the audience could see the movement of the hands. An ink bottle, a 

 flower, parts of a theater hand-bill, were also shown, and when the head of a live 



