Let us hope that science will not advance so far as to lay- 

 bare our thoughts by registering the molecular changes in the 

 brain. It would add a new terror to life and the very idea would 

 seem to fortify the arguments in favour of cremation. 



From time to time we hear that one thing long desired by 

 nr.any has been done, and that the production of a coloured photo- 

 graph has been accomplished. Hitherto their hopes have been 

 dashed as soon as raised. M. Becqurel succeeded in obtaining 

 coloured impressions by converting the surface of a Dagerreotype 

 plate into violet sub-chloride of silver. But this coloured image 

 cannot be fixed, so that when exposed to the light it vanishes. I 

 pass over M. Joly's process since it includes the painting of the 

 positives with pigment — an idea foreign to what is meant by a 

 coloured photograph. But a real step forward has now been 

 made by M. Lippmann who has succeeded to a certain degree, by 

 placing a mirror in the shutter behind the negative glass. The 

 rays of light are thereby stopped in their career and thrown back 

 on the ray following them — otherwise the incident rays. The 

 effect is that parallel to the surface of the plate a series of strata 

 is formed which strata vary according to the intensity of the 

 energy of the rays which have met on its surface. Two 

 necessaries were wanting — firstly, a transparent film to admit the 

 the rays of light to the mirror — and secondly, a close and 

 immediate contact between the mirror and the film. The first 

 requisite was after considerable trouble conquered by increasing 

 the amount of the organic substratum of gelatine or albumen. 

 The second requisite — viz., a mirror in perfect contact was found 

 by pouring mercury into a reservoir behind the plate — so that the 

 film being reversed (as would of course be necessary) it is 

 in immediate touch with the mercury. 



This plate is exposed^ developed, and fixed in the usual 

 way, but the colours so produced can only be seen at the angle 

 of specular reflection. They are so far permanent that they can 

 be called up at any moment. Wet the surface of the plate and 

 they disappear, to come forward again as the plate gradually 

 dries. 



Another achievement is the discovery of Argon. In his paper 

 on the theory of Phlogiston, published in the Philosophical Tran- 

 sactions in 1784, Cavendish showed that he suspected the nitrogen 

 of the atmosphere to be not all of one quality, and since the time 

 of that great scientist the question remained unanswered until 

 now, when two of our leading men. Lord Rayleigh and Professor 

 Ramsay, working at first independently, have solved the problem 

 and have produced a gas which from its inertness has been named 



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