Progress of Invention. 145 



the designs, as before, "by the electrotype. As no two crystalliza- 

 tions are exactly alike, and they cannot possibly be copied by the 

 engraver, nor by the photographer, if coloured ink is used, it is 

 considered that printing them from the electro-plates on bank- 

 notes would afford a great additional protection against forgery. 



Improved Thermo-Electric Pile. — Up to this time, bismuth 

 and an alloy of antimony have been considered the very best ele- 

 ments for thermo-electric piles. Professor P. Bunsen has, how- 

 ever, recently found that pyrolusite may be employed with far better 

 effect than bismuth, and copper pyrites, with far better than pyro- 

 lusite. The pyrites must be used in the natural state, since fusion 

 reduces its power below that of bismuth ; but it is easy to form it 

 into a plate of the required size. It was 1 found that a pair con- 

 sisting of a plate of copper pyrites seventy milimetres long, forty 

 broad, and seven thick, with two copper pins, platinum plated, in- 

 serted into it at a distance of thirty- five milimetres from each other, 

 the upper pin having a projection which was heated by a non- 

 luminous lamp flame, while the lower edge of the plate was 

 placed in water, afforded a ten times greater effect than a pair con- 

 sisting of antimony and bismuth ; and a combination consisting of 

 ten such pairs produced all the effects of a Daniel battery, having 

 a copper surface of fourteen square centimetres. During these 

 experiments, the pyrites was heated above the melting point of tin 

 without undergoing any change. Copper pyrites and platinum 

 affords also an excellent pile. 



Metallic Coating, so as to Produce a White Surface. — This 

 is effected in a very simple way, by M. Weil. He makes an alka- 

 line solution of the metal which he intends to deposit, and adds to 

 it tartaric acid, glycerine, or some other organic matter. Iron, 

 steel, etc., may with such a fluid be coated with copper, zinc, 

 nickel, etc., and beautiful bright surfaces be obtained. It is usually 

 sufficient to place the object to be coated in the alkaline solution ; 

 but, if required, a weak galvanic current may be generated, by bring- 

 ing it into contact with a piece of zinc. 



Lucifer Matches. — There are many reasons which make it 

 highly desirable that phosphorus should be rendered unnecessary 

 in the manufacture of matches. Phosphorus produces one of the 

 most terrible diseases of the jaw in those who manufacture it. No 

 doubt this would not occur were amorphous phosphorus employed ; 

 but the latter is dearer, and how few are there so philanthropic as 

 to pay more than is absolutely necessary for anything they require. 

 Also phosphorus, especially the ordinary kind, is highly combus- 

 tible. How many buildings have been burned, how many lives lost 

 through the careless treatment of lucifer matches ! Lastly, phos- 

 phorus is one of the essential elements of plants and animals, 

 though it is found in comparatively but small quantities. It is 

 highly mischievous, therefore, to place vast quantities of it in cir- 

 cumstances in which it is scarcely possible for it again to return 

 to the soil, where it is so much needed. Two German chemists 

 seem to have made good lucifer matches, containing no phosphorus. 

 One of them, Dr. H. Poltzer, uses for the match heads a mixture of 



