518 



SCIENCE. 



[N. S. Vol. IX. No. 223. 



It was fouud that fuller's earth had a se- 

 lective affinity for caramel coloring matter in 

 spirits, while the natural color derived from 

 wood was but slightly affected. The test is 

 made by beating up twenty-five grams of the 

 earth with fifty cc. of the sample to be tested, 

 allowing it to stand for thirty minutes at room 

 temperature, and filtering. The color before 

 and after treament is observed by means of 

 Levibond's tintometer or other form of good 

 colorimeter, and the amount of color removed 

 ascertained in this way. 



The test was applied to all the samples of 

 ^spirits available in the laboratory of internal 

 revenue, positive results being obtained in all 

 cases. A series of 40 samples known to be 

 naturally colored gave an average of 14.6 per 

 cent, of color removed, while 18 samples of 

 spirit known to be colored with caramel aver- 

 aged 44. 7 per cent, of color removed. 



The test was also applied to a few samples of 

 vinegar, with good results. 



The second paper of the evening was read by 

 Dr. David T. Day, and was entitled ' Charac- 

 teristics of Iridosmium in, the United States.' 



A demand has lately arisen for this mate- 

 rial as a source of osmium, with which it is pro- 

 posed to impregnate the filaments of incandes- 

 cent lights, with most beneficial results as to the 

 amount of light supplied by a given current and 

 the increased life of the lamp. The problenLof 

 supplying a large amount of osmiridium is a most 

 fascinating one and has led to much study in the 

 localities of the West where platinum metals 

 have been found. The results show that plat- 

 inum is much more generally distributed through 

 'the western placer mines than was supposed 

 and that there are localities containing so-called 

 cx-ude platinum, in which osmiridium is found. 

 A sample sent from the Oregon beach contained 

 as high as 99 per cent, of osmiridium. The 

 Hay Fork District, inTrinity county, California; 

 Junction City, and more especially the whole 

 Pacific Coast beach, is a most interesting field of 

 search because the platinum is mixed with much 

 osmiridium. It can be said in general that 

 nearly all the crude platinum sand contains os- 

 miridium in greater or less quantity, according 

 to the analyses of a great number of sands made 

 by Dr. Waldrou Shapleigh, for the Welsbach 



Light Company. An interesting exception is 

 the Granite Creek District, of British Columbia. 

 A curious form of osmiridium was noted at the 

 Chapman Mine, near Junction City, California, 

 where nuggets i inch in diameter, when treated 

 with Avarm dilute nitro-hydrochloric acid, yield 

 platinum in solution and flakes of osmiridium. 

 The separation of the platinum from the os- 

 miridium is readily accomijlished by means of 

 nitro-hydrochloric acid, and the separation of 

 osmic acid from the residue is quite simple by 

 the ordinary process of passing chlorine over the 

 osmiridium mixed with salt. The purification 

 of the osmic acid is now effected by redistilla- 

 tion, but it is probable that these methods will 

 be much improved within the next few months. 

 It is probable that 2,000 ozs. of the material will 

 be obtained during 1899. 



The last paper of the evening was read by Dr. 

 Day, and was entitled ' Uses of Fuller's Earth 

 as a Filtering Medium.' 



In 1892 an eflPort was made by the Owl 

 Cigar Manufacturing Company at Quiucy, 

 Florida, to manufacture brick from a peculiar 

 cream-colored clay found on their property. 

 Instead of baking hard, it exfoliated in a pecu- 

 liar manner and caused some comment from an 

 Alsatian cigar-maker in the employ of the com- 

 pany, who noticed this clay and called atten- 

 tion to its close resemblance to German fuller's 

 earth. This led to an inquiry as to its value as 

 fuller's earth, at a time when the lubricating oil 

 companies were looking for domestic fuller's 

 earth to replace animal charcoal as a means of 

 lightening the color of lubricating oils by filtra- 

 tion. The earth proved very suitable, and its 

 use extended in this direction as well as to some 

 extent in the bleaching of vegetable oils. But 

 for the latter purpose the imported fuller's earth 

 is still approved. The number of samples of 

 clays which have been called fuller's earth and 

 sent to the consumers for examination since 

 that date is almost beyond belief. It has been 

 shown that fuller's earth is quite widely scat- 

 tered in the northwestern counties of Florida 

 and the adjacent counties of Georgia. In the 

 latter region the fact that it grades into chalce- 

 dony makes it more probable that the fuller's 

 earth is a chemical precipitate, and this is further 

 indicated by the replacement of calcium car- 



