July 28, 1893.] 



SCIENCE. 



47 



carbonado. The diamond is rapidly dissolved when heated to a 

 high temperatui'e with carbonates of the alkalies, carbonic acid 

 being given off, but no hydrogen, and hence M. Moissan con- 

 cludes that diamonds contain no hydrogen or hydrocarbons. 



Treated with hydrofluoric acid, and then with aqua regia and 

 finally washed, dried and burnt in oxygen, the diamonds yielded 

 an ash consisting in all cases but one chiefly of ferric oxide. 

 Cape bort contained also silica, calcium and magnesium, and 

 Brazilian carbonado, silica and calcium, with a trace of magne- 

 sium. One specimen of green transparent bort from Brazil left a 

 minute quantity of ash, which contained silica, but no iron. 



Preparation of Pure Alumina. 



The preparation of pure alumina from bauxite, which is al- 

 ways accompanied by more or less silica and oxide of iron, has 

 commonly been carried out as follows: Taking advantage of 

 that property of alumina, which enables it to act as either base 

 or acid, according to its environment, the bauxite is fused with 

 sodium carbonate, the resulting products being sodium aluminate 

 and sodium silicate. The mass is then extracted with water and 

 the sodium aluminate passed into solution. The silicate of soda, 

 owing to a deficiency of base, is but little acted upon by the 

 water and with the ferric oxide is left in the residue. From the 

 solution of the sodium salt the alumina is precipitated by passing 

 carbonic acid gas, carbonate of soda being regenerated at the 

 same time. 



This process has lately been improved by first precipitating a 

 portion of the solution of aluminate by the gas in the cold, pro- 

 ducing a small quantity of crystallized alumina hydrate of the 

 same composition as Gibbsite, Al^Oa 3 HgO. This, then, is added 

 to the main bulk of solution, and a complete separation of the 

 whole is secured, the soda being left in the caustic state. The re- 

 action which takes place has been investigated by M. A. Ditte, 

 and is explained as follows: A solution of sodium aluminate may 

 be regarded as amorphous hydrated alumina dissolved in caustic 

 soda. The form in which a body crystallizes from a solution is 

 largely determined by the character of the crystal introduced to 

 start crystallization. Hence in the process described above the 

 tendency of the whole is to crystallize in the form of the several 

 crystals first introduced, and as the crystalline form of alumina 

 is less soluble than the amorphous in alkaline solutions, there is 

 a gradual complete precipitation. Stirring facilitates the separa- 

 tion of the crystals by bringing those already formed into contact 

 with fresh portions of solution. There is finally left only that 

 proportion of alumina corresponding to the solubility of Gibbsite 

 in caustic soda under the conditions existing, 



Silk from Wood. 



At the Paris Exposition in 1889 M. de Chardonnet gave to the 

 world his process for the manufactirre of silk from wood and re- 

 ceived the highest honors from the jury of award. Since that 

 time the process has been further developed and has presumably 

 attained a practical success; silk is being manufactured at Be- 

 sangon from wood pulp such as is used in the fabrication of cer- 

 tin kinds of paper According to F. B. Loomis, U. S. Consul at 

 St. Etienne, the following process is used : The pulp is carefully 

 dried in an oven and plunged into a mixture of sulphuric and 

 nitric acids, then washed in several water-baths and dried by alco- 

 hol. The product thus prepared is dissolved in ether and alcohol 

 with the production of collodion similar to that used in photogra- 

 phy. This collodion, which is sticky and viscous, is enclosed in 

 a solid receptacle furnished with a filter in the lower end. An 

 air-pump supplies air to the receptacle, and by its pressure forces 

 the collodion through the filter, removing all impurities. The 

 collodion flows into a horizontal tube armed with three hundred 

 cocks having glass spouts pierced by a small hole of the diameter 

 of the thread of a cocoon as it is spun by the silkworm. The 

 spinner opens the cock and the collodion issues in a thread of ex- 

 treme delicacy. This thread, however, is not yet fit to be rolled 

 upon spools on account of its viscosity and softness, being still 

 collodion and not "silk." To obtain the necessary consistency 

 the thread as it issues is passed through water, by which means 

 the ether and alcohol are washed out and the colloJion s-ollJified 



and transformed into an elastic thread as brilliant and resisting 

 as ordinary silk. The dangerous inflammability of this substance, 

 as prepared above (two centimetres per second), has been reduced, 

 according to the inventor, by passing the spun thread through a 

 solution of ammonia, thus rendering it as slow of combustion as 

 any other like dress material. 



Up to January of this year none of the more important silk 

 manufacturers of St. Etienne or Lyons had invested heavily in 

 this enterprise, but all express confidence in the process and be- 

 lieve it is destined to figure largely in the commercial world. 



New Method for Melting Points. 



A. Potilitzin is the author of a new method for the determina- 

 tion of the melting points for substances melting below 450°, this 

 being the highest temperature which a nitrogen-filled mercury 

 thermometer can indicate. One end of a hard-glass tube, 5 mm. 

 bore and 500-600 mm. in length, is drawn out to capillary fine- 

 ness and the other is bent at right angles. The capillary is dipped 

 into the molten substance, the melting point of which is to be de- 

 termined, so that on cooling the tube is closed by a solid plug of 

 the substance 3-4 mm. long. The other end is connected with a 

 manometer by means of which a pressure exceeding that of the 

 atmosphere is maintained within the tube. The tube, along with 

 the principal thermometer and also one for stem correction, is in- 

 serted into a wide test-tube, which is then immersed in a bath of 

 fusible metal. When the melting-point is reached the plug soft- 

 ens and is expelled by the internal pressure, so that the sudden 

 equalizing of the pressure in the manometer indicates the mo- 

 ment when the substance melts, the thermometers being then 

 read off. Potassium nitrate was found by this method to melt at 

 336.57° (mean of eight experiments); by immersion of the ther- 

 mometer direct into a large mass of the salt the melting point 

 was found to be 336°. 



Pigments Used in Some India-rubber Toys. 



India-rubber has been generally, and correctly, accepted as a 

 suitable material for children's toys; but investigation into the 

 manufacture of the latter reveals the fact that many as placed 

 upon the market contain harmful ingredients. A. Bulowsky has 

 recently called attention to several dangerous ingredients as, for 

 instance, in black dolls, which are often colored "in the mass " 

 with lead pigments. Red articles are also most usually c'oloredin 

 mass, the pigment being antimony sulphide, which, however, 

 being unattaoked by the saliva may be considered innocuous. 

 Grey rubber goods generally contain zinc oxide, and hence par- 

 ticularly when, as is sure to be the case, the toy is brought to the 

 child's mouth, an element of danger is introduced. Superficial 

 coloring is frequently accomplished by means of poisonous pig- 

 ments. These remarks are applied in particular to foreign manu- 

 factures, and though, doubtless, the same coloring matters are 

 used in this country, I have yet to learn of a case of poisoning 

 from coloring in mass. Superficial pigments, from their dispo- 

 sition to flake and from the greater quantity brought into contact 

 with the mouth, are certainly to be avoided. It is difficult, 

 moreover, to estimate the amount of damage done by these toys 

 owing to the many petty ills and derangements of infancy, the 

 poison received by the child very likely is insuflScient to develop 

 well-defined symptoms or to direct suspicion, but at the same 

 time may be the cause of an indisposition which itself brings on 

 crying, wakefulness, and general wear on the little body strug- 

 gling for existence. 



NOTES AND NEWS. 



Professor E. W. Doran has been elected president of Buffalo 

 Gap College, Buffalo Gap, Texas, and has resigned his position 

 at College Park, Md. 



— C. H. Turner has resigned his position at the University of 

 Cincinnati and accepted the Chair of Natural History at Clark 

 University, Atlanta, Ga. 



— P. 21, line 9, from below: " regristation," read "registra- 

 tion;" p. 23, line 15, from below : "possible," read " impossible;'' 

 and p. 22, column 2, line 31, from above: "understood," read 

 '• understand." 



