CHFMICAL SCIENCE. 217 



Ancient Stained Glass. — It has been found that the colors of 

 ancient stained glass may be completely restored by leaving it 

 immersed for several days in a solution of carbonate of soda, 

 which dissolves away the organic matter to which in part the 

 dimness produced by age is due, and then immersing it for several 

 houi'S in dilute muriatic acid to remove the mineral substances, 

 which also impair the brilliancy of the colors. 



Magnesium. — Magnesium light contains an extraordinary pro- 

 portion of ultra-violet or chemical rays, this part of the spectrum 

 between the extreme violet and tlie extreme red being six times 

 as large as usual, and it is particularly efficient for producing 

 fluorescent and photograpliic effects. Vei*y remarkable fluor- 

 escence may be obtained by exposing to the light a paste made 

 of powdered platino-cyanide of barium and gum arable. 



Nature of the Diamond. — Goeppei't, in his published essay on 

 the " Organic Nature of the Diamond," shows that it cannot be of 

 igneous origin ; for it turns black when highly heated. Moreovei', 

 it contains sometimes, beside other crystals, germs of fungi, and 

 vegetable fibres of higher organizations. 



American Sienna. — A valuable repository of this precious pig- 

 ment exists in the town of Whately, Conn., which will soon be 

 brought into extensive use. 



Passive State of Metals. — The so-called passive state of metals 

 has been proved by Dr. Heldt to result from the formation of an 

 insoluble film, differing in dift'erent cases, but alwa^'s protecting 

 the metal from the attack of the acid or other solvent. 



NEW AND BAKE MINERALS. 



Laurite ; a New Mineral. — Wohler has discovered among the 

 fine-grained platinum ore from Borneo, a new mineral, a sulphide 

 of ruthenium and osmium, to which he had given the name of 

 Laurite. It occurs in small grains of a dark iron black color and 

 high lustre. Most of the grains are true crystals, and Sartorius 

 has recognized the mineral to have the form of the regular octo- 

 hedron, in some instances showing cubic, tetrahexahedral, and 

 other planes. It is brittle, yielding a dark gray powder on pul- 

 verization ; hardness above that of quartz ; specific gravity G.99 ; 

 decrepitates when heated ; infusible before the blowpipe. Analy- 

 sis gave ruthenium 65.18, osmium 3.03, sulphur 31.79 (approxi- 

 mate). Formula Ru2 S3 91.8, Os S4 8.2. This is the first instance 

 of the occurrence of a natural sulphide in the group of platinum 

 metals. — Ann. Cliem. Pharm., 139, IIG. 



Pachnolite. — Knop has recently discovered in the decomposed 

 and weathered cryolite a new mineral, to which he has given the 

 name of Pachnolite, from its resemblance to hoar frost. He gives 

 the chemical composition as Fl. 50.79, Al. 13.14, Na. 12. If), Ca. 

 17.25, H. 9. GO = 102.94. Dr. G. Hagemann, of the Alkali Works 

 at Natrona, Penn., has examined this mineral, and fully confirms 

 JNI. Knop's results. Cryolite is now largely imported to Natrona 

 from Greenland, for the purpose of manufacturing soda-ash, 

 alumina salts, and other products. — American Journal of Science. 

 19 



