M. Gaudin on the artificial production of Rubies. 563 



A portion of this acid was dissolved in alcohol of sp. gr. *915. This 

 solution had the following properties : it reddened litmus paper, and 

 precipitated the following salts; the proto-and persulphate of iron, ni- 

 trate of silver, acetate and subacetate of lead, the chlorides of barium, 

 lime, and platin urn , but not that of magnesium ; and sluphate of copper ; 

 the aqueous solution of tannin formed a light precipitate. The aqueous 

 solution of the acid precipitates the same salts. The solution exposed 

 to the air evaporated without giving any traces of crystallization. 

 Another spirituous solution of this acid, saturated with potash, left by 

 spontaneous evaporation a very bitter white mass, in which no trace 

 of crystallization could be observed. 



Concentrated sulphuric acid causes this acid to impart a weak violet 

 tint to water. 



This modified acid considerably resembles the oxalic acid of M. Fres- 

 ny, [differing only in two of its properties ; that of gelatinizing under 

 peculiar circumstances, and of giving a bitter compound with potash. 

 These differences are constant, by whatever mode the acid may have 

 been prepared. — Ibid. 



ARTIFICIAL PRODUCTION OF RUBIES. 



A few months since M. Gaudin presented to the Academy of 

 Sciences of Paris a note, in which he announced his having been able 

 to produce rubies in considerable quantities by a process of which he 

 has given merely a sketch. 



In order to obtain these substances analogous to rubies, M. Gaudin 

 uses a platinum blowpipe of a single piece, formed of two hollow con- 

 centric cylinders, communicating by one of the extremities, one with 

 a reservoir of hydrogen, the other with a reservoir of oxygen j the 

 two other extremities are pierced with convergent openings, so as to 

 effect in a great degree the mixture of the gases. 



It is well known that alumina is fusible with the oxygen and hy- 

 drogen blowpipe j but no one before M. Gaudin had endeavoured to 

 melt this earth into globules several millimetres in size. Having sub- 

 mitted a piece of potash alum to the action of his blowpipe, he ob- 

 tained a perfectly round and limpid globule The platinum tube being 

 perforated and melted at several places, he obtained after the cooling, 

 instead of a limpid spheroid, an opake elongated globule, and covered 

 internally with crystals, which may be referred to the cube or to the 

 rhombohedron. These crystals scratch- rock crystal, topaz, garnet, and 

 spinelle; with regard to hardness, therefore, they agree with the ordi- 

 nary ruby. They appear to be composed solely of alumina, the potash 

 volatilizing at the high temperature to which the alum is submitted. 



Having obtained an apparatus stronger than the one first used, he 

 made an experiment with some ammoniacal alum mixed with from 

 4 to 5 thousandths of chromate of potash ; the whole being previously 

 calcined, he gave it the form of a spherical cup, in order to obtain a 

 maximum effect, by directing the flame to the concave part. In a few 

 moments the inner surface of this cup was covered with globules of a 

 beautiful ruby-red colour, slightly translucid, and some of which ex- 

 hibited the form and cleavage of the ruby. 



M. Malaguti, who had occasion to analyse these globules, found 



4C2 



