POPULAR MISCELLANY 



251 



ceased entirely. His arrival in the village, 

 with the story of his adventure, created 

 quite a sensation ; but, when the bird was 

 deposited on the ground to be examined at 

 leisure, it revived for the third time, struck 

 its claws through the hand of its captor, 

 struggled to its feet, and would have es- 

 caped after all, if the enraged miner had 

 not fiung himself upon it, seized a stone and 

 hammered its head to a jelly. 



Muslin Glass. The mode of producing 

 so-called "muslin glass" is as follows: 

 After carefully cleaning the surface of a 

 plate of glass, a layer of verifiable color is 

 laid over it, the vehicle being gum-water, 

 and care being taken to have the pigment 

 evenly applied. The glass is then submitted 

 to a gentle heat until the water has evapo- 

 rated, when a stencil of the desired pattern 

 is laid over the surface, and with a stiff 

 brush the pigment is removed from the 

 parts which are to be transparent. The 

 glass is next inclosed in a frame, and above 

 it is extended a piece of tulle or, if desired, 

 embroidered lace, the embroidery in the lat- 

 ter case being so disposed as to harmonize 

 with the ground-pattern previously made. 

 The whole is then hermetically closed in a 

 box which contains in its lower portion a 

 reservoir holding a certain quantity of dry 

 color in the form of impalpable powder. 

 This by an air-blast is blown evenly upon 

 the glass and adheres to the latter wher- 

 ever the surface is not protected by the 

 threads of lace. In this way the pattern of 

 the latter is defined. In order to fix the 

 powder, the sheets of glass are placed in a 

 steam-chamber where the steam moistens 

 the gum and causes the powder to adhere. 

 The color is then burned in a special fur- 

 nace. 



Variability of the Nebnlse. In a lecture 

 recently delivered at Paris, under the au- 

 spices of the Scientific Association of France, 

 the eminent Swiss astronomer Wolf gave an 

 account of recent researches on the " vari- 

 ability of the nebulae." His conclusions, as 

 stated in La Nature, are : that some of the 

 nebulae are certainly in a state of relative 

 motion at least one double nebula being 

 known to astronomers, the component parts 

 of which revolve about each other ; that in 



all probability some of the nebulae are wan- 

 ing and disappearing as instances of this 

 he cites three nebulae in the constellation of 

 Taurus ; that possibly some of the nebulae 

 are undergoing a change of form ; the spi- 

 ral nebula in Canes Venatici appears to af- 

 ford an illustration of this fact. As for the 

 distances of the nebulae, they cannot yet be 

 determined, but there are grounds for believ- 

 ing that many of them are not more remote 

 from us than the fixed stars. 



Copying Designs by Photography. A 



new process of making photographic copies 

 of machinery, drawings, plans, maps, etc., in 

 blue lines on a white ground, has been in- 

 vented by H. Pellet, a chemist of Paris. 

 This process (says La Nature) is based on 

 the peculiar property possessed by per- 

 chloride of iron, whereby it is converted 

 into protochloride by exposure to light. 

 The protochloride is not affected by contact 

 with prussiate-of-potash solution, but the 

 perchloride at once becomes blue. M. Pel- 

 let sensitizes a sheet of paper by dipping it 

 in a bath consisting of water 100 parts, per- 

 chloride of iron 10 parts, oxalic or some 

 other vegetal acid 5 parts. In case the 

 paper was not sufficiently sized, gelatine, 

 isinglass, dextrine, or some such substance, 

 would have to be added to this solution. 

 The paper so treated M. Pellet calls it now 

 cyanofer-paper is dried in the dark, and 

 may then be kept for a length of time. It 

 is very sensitive to light. To make a copy 

 of a drawing made on transparent paper, 

 the drawing is spread over a dry sheet of 

 the cyanofer, a plate of glass laid over all, 

 and the whole exposed to the light. In 

 summer, with exposure to the full sunlight, 

 it takes from fifteen to thirty seconds to de- 

 compose so much of the perchloride of iron 

 as is not protected by the lines of the draw- 

 ing. In winter, an exposure of forty to sev- 

 enty seconds is necessary. In the shade, 

 in clear weather, the exposure varies from 

 two to six minutes, and in cloudy or rainy 

 weather, from fifteen to forty minutes. The 

 electric light may be used instead of sun- 

 light, the time of exposure varying accord- 

 ing to the intensity of the light and the dis- 

 tance. After exposure, the paper is dipped 

 in a bath of prussiate of potash (15 to 18 

 per 100 parts of water), and it at once as- 



