148 Notes and Memoranda. 



the atmosphere again before escaping behind the earth, and that thus the illumi- 

 nation of the atmosphere diminishes the earth's shadow by more than twice the 

 diameter of the moon. The bent rays are the first to reach the moon as she 

 emerges from the shadow. As the refraction is proportioned to the density of 

 the air, those rays which traverse the atmosphere at a considerable elevation are 

 less bent than those which pass close to the earth. On the 1st of June the solar 

 rays passed over the earth's surface in the middle of Greenland. In the western 

 part of the circle of illumination the rays traversed the air above glaciers which 

 have an elevation of at least 500 meters, while at the eastern part they traversed 

 the air close to the open sea, and having a refractive power of seventy minutes, 

 that of the air above the glaciers being refracted at least four minutes less. This 

 accounts for light reaching one part of the lunar crescent before the other. 



An Innocent Green. — Cosmos gives the following as the composition of an 

 innocent green for house painting and paper hanging, and which ought to replace 

 the poisonous arsenical greens. It is called " English green," and contains — 



Sulphate of baryta . . . 0780 



Protoxide of iron . . . 0040 j 



Silica 0-088 



Alumina .... 0-040 



Soda ..... 0025 



Lime 0007 



Water and loss . . . 0-020 



1-000 



New Process of Engraving. — Cosmos gives the following as the process of 

 M. Dulos : — A plate of copper is covered with a varnish of india-rubber and 

 zinc white. Lines are traced through this surface down to the metal by an ivory 

 point. The plate is then plunged in a solution of hydrochlorate of ammonia, the 

 positive electrode being a plate of iron in communication with the negative pole 

 of the pile. Iron is deposited on all the parts of the copper exposed by the ivory 

 point, but not on the varnish, which is removed by benzine. The plate is once 

 more exposed to electric action in a bath of silver, and that metal is precipitated 

 on the copper but not on the iron. It is then heated to 80° C, and an alloy 

 fusible at that temperature is poured over it. The liquid moistens the silver and 

 adheres to it, but not to the iron, which it does not moisten. When cold the 

 fusible alloy will be found standing on each side of every line, and forming a 

 mould, from which a new plate, adapted to printing, is obtained by a galvano- 

 plastic process. 



Reproduction of LiTnoGiurns. — The following note from M. Rigaud has 

 been presented to tho French Academy : — " I apply the back of a lithograph to a 

 layer of pure water for a few minutes ; it moistens uniformly, and the water does 

 not wet tho black portions. I withdraw it and place it between two folds of 

 paper to removo excess of moisture, and then stretch it face downwards upon a 

 lithographic stone, to which it adheres by slight pressure. I then take a sheet of 

 ordinary paper and moisten it with tho nitric acid of commerco diluted with ten 

 times its bulk of wafer. Removing the superfluous acid by two folds of paper 

 as before, I press this acidulated sheet upon the lithograph. The nitric arid 

 work* its way slowly through the moistened lithograph, and acts uniformly on 

 tho stone with disengagement of carbonic acid gas, which penetrates the pores 

 of the paper as last as it, is produced." 



Lionm, l!i:\u: OB Nkkvk Cells.— Mr. Bcalc's researches lend to the con- 

 clusion, "1. That in all eases nerve fibres are in bodily connect ion with the cell 

 or celll which influence limn, and this from the earliest period of (heir formation. 

 2. That there arc DO apohn- cells, and no unipolar cells in any part of any nervous 



system. B. Thai every nerve cell, centra] or peripheral, has at least two fibres 

 connected with It."— Proceedings of the "Royal Society, No. 56. 



