Maech S8, 190ii.J 



SCIENCE. 



513 



charum Marshall for the sugar maple (not A. 

 saccharinum Wang). In both numbers the 

 illustrations are of the high order of the pre- 

 ceding f/ef /en. Charles E..Bessey. 

 Thb University of Nebraska. 



'NOTES ON INORGANIC CHEMISTRY. 

 The first two numbers of the Zeitschrift fur 

 Blectrochemie for January contain an experi- 

 mental investigation by F. Haber and R. Gei- 

 pert on the preparation of aluminum. The 

 authors used as a crucible a block of coal 

 245 X 245 X 1'''5 mm., the opening having a 

 diameter of 113 mm. at the bottom, 138 mm. 

 at the top, and 70 mm. deep. This crucible 

 served as a kathode, and a rod of coal 66 mm. 

 in diameter as anode. The bath consisted of 

 an artificial cryolite containing somewhat less 

 than the theoretical amount of sodium fluorid, 

 and in this pure alumina was dissolved. The 

 most favorable current was 3 amperes per 

 square centimeter at 7 to 10 volts. Under 

 these conditions the electrolysis proceeded as 

 smoothly and regularly as in the ordinary 

 electro-analytical precipitation of a metal. 

 Although the density of the solid bath is 

 slightly greater than that of aluminum, when 

 fused it is slightly lower. If, however, too 

 much alumina is dissolved in the bath, it 

 becomes too dense and the aluminum, instead 

 of sinking, floats, often short-circuiting the 

 current. A higher percentage of aluminum 

 fluorid than is present in natural cryolite is 

 advantageous, as it renders the bath more 

 fusible. The output varied from 50 to 55 per 

 cent, of that theoretically required by the 

 current. The aluminum prepared was of par- 

 ticularly pure quality, and in the opinion of 

 the authors the production of the same qual- 

 ity on a large scale is possible by the use of 

 pure materials and an anode low in ash. It 

 was found necessary to add fluorid to the bath 

 from time to time to replace that which is 

 lost by a gradual volatilization. 



The modern manufacture of tin foil is 

 described by Rafael Gran j a in the Journal 

 of the Society of Chemical Industry. Three 

 varieties of tin foil are on the market: pure 

 tin foil, composition foil, and Dutch leaf. 

 The composition foil consists of lead, covered 



on both sides with a thin coating of tin, while 

 the Dutch leaf is prepared from an alloy of 

 tin with a few per cent, of a secret metallic 

 composition. The grade of fineness of the 

 foil is expressed by the number of square 

 inches which a pound of the foil will cover. 

 Thus the limit reached by the thinnest pure 

 tin foil is 10,000, by composition foil 7,000, 

 while Dutch leaf reaches 14,000 square inches. 

 The manufacture of the foil, and also of the 

 capsules for the tops of bottles, is fully 

 described in the paper. 



From the Physiological Laboratory of the 

 Veterinary High School of Vienna comes a 

 contribution, which indirectly contributes to 

 our knowledge of the occurrence of iodin in 

 soils, and especially with reference to the 

 question as to whether it is largely confined 

 to those soils which are near the sea. On 

 examining the thyroid glands of sheep from 

 different Hungarian localities, Wohlmuth 

 finds that the percentage of iodothyrin — 

 0.2-0.35 per cent. — is approximately the same 

 as that found by Baumann in German and 

 French sheep, and that the iodothyrin con- 

 tains about the same amount of iodin — 3.2-3.3 

 per cent.- — as that obtained by Baumann. 

 The sheep from these far-inland localities 

 must therefore have found in their food the 

 necessary quantity of iodin for a normal 

 amount of normal iodothyrin. 



Thu work of Liversidge on the crystalline 

 structure of metallic nuggets has already been 

 noticed in these columns. This work has been 

 continued by the examination of a number of 

 new specimens. The structure is studied by 

 etching a polished surface of the metal. In 

 nuggets from Lake Superior containing both 

 silver and copper, it appears that the silver 

 has been deposited upon the copper. Gold 

 nuggets from the Klondyke present a struc- 

 ture and appearance quite different from those 

 of any other locality. They are very pale in 

 color, owing to the large quantity of silver 

 present. An assay of two specimens gave 

 only sixty-five per cent, of gold. In the case 

 of silver and copper nuggets, as has been found 

 with those of gold and platinum, there is every 

 indication that the metal has been deposited 



