INDUSTRIAL A S D ENGINEERIAVGCUEMlMTRY
February, 1921
being filled with solder. This facilitates cleaning. The re. ceiving cup and lower disk are removable and the upper disk is held in place by a hinged crosspiece on the frame. a n adjnsting nut at the top of the stationary disk permits regulation of t.he distance between the plates, and a strong spiral spring imparts the necessary pressure to thc grinding surfaces. The framcwork is constructed of wood 3 inches thick, except for the hinged member carrying the upper disk. which is inches t,hCck. When assembled the mill and frame are 17l/4 inches thick and 25 inches lone. (Figs. 2, 3, and 4.) The upper disk is screwed on to a piece of 1-inch pipe, which provides means for both mounting the disk and charging the mill. The finely ground material is whirled from the rotor to dlie receiving cup, from which it can he drawn off through the the particles in the origidrain pipe to n beaker or flask. If nal material are large, it is advisable to adjust the disks some distance apart at first and pass the suspension through several times, hringing the disks closer together after each pass. By this treatment a very fine suspension can be ob-
127
per. A 50-gvst.te sample of the ground material is suspended in about 200 cc. of boiling water and passed through the mill as many times as neeessary. In tk.3 case of raisins three times will umally suffce. The disks and receiving cup are then washedwith successive additions of warm water while the mill is running,.until all materials are washed into the receiving beaker or flask. The suspension and washings are cooled in running water and made up to 500 cc. volume a t 20” C. If analyses are not to hc made immediattly, four or five d r o p of iiilueir ihould hc added to prevent the dwelopment of moldi
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Freiwli I’liysical Society Anniversary
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I-RELATION OP REYUCTIVC I N ~ IOX CONCCNIIATION or RBDUCTNC Suonas IN Ratsm S ~ L V T I O N PRGPARED S ET mxp. COLLDID Mt%&
tained in a surprisingly short time. The resulting suspension can then be subjected to any analytical procedure desired.
DETERMINATION OF RAI~IN SUGARS To insure uniform sampling and facilitate grinding, ahout 200 grams of raisins are passed through an ordinary food chop-
The srmicentemiial of the organization of La Societb FranEnise de Physique was celebrated in Paris, Dccember 10 t o 15, by a series of lectures by distinguishcd physicists given in the Amphitheatre de Physique a t thc Sorbonne, and by other functions. The most interesting lecturer were by Loreriz on “The New Mechanics:” Lord Rayleigh on “Iridescence;” Stormcr on “The Aurora Borealis;” and by Knudseii oil “The Mechanism of Evaporation and Condensation.” On Wednesday eveninp, the lZth, there was an elegant banquet a t which several hundred physicists from the principal couiitries of Europe were present. Thursday aitemoon, the 13tl1, there was a ”Sbance Solennelle” i n , the Grand Amphitheatre 0% the Sorbonne, with Alerandre Mdlerand, President of the Republic, in the chair. On this occasion, in addition to addresser on the history of the society, there was an address by Charles Fabry on “Explorations in the Field of Radiation.” An exposition oi physics in the Grand Palais, which was oripinally planned to last for two weeks, proved to be so popular that it was continued for a third week. The exposition contained both scientific and commercial exhibits from all fields of physics. the exhibition oi electrical apparatus being especially prominent. The entertainment of delegates t o t h k celebration was provided for with true French hospitality.-W. A. NVYES
