42 REPORTS ON THE STATE OF SCIENCE.—1918. 
. the researches of Perrin and others. By adding a trace of caustic 
alkali to the peat mud, the dewatering is greatly hastened.1® He has 
also devised an interesting electro-osmotic filter press!” in which peat 
or clay are dewatered under pressure between filter diaphragms and 
an electric current sent through. It is claimed that by continuous 
pressure and electrical endosmose, the pressure necessary to filter 
clay or peat suspensions may be reduced twenty fold. Further 
improvement is said to be gained by disintegrating!® in a ball mill 
the peat as it comes from the bog and adding the electrolyte to the 
mill. 
THE “OSMOSE”’ PROCESS OF PURIFYING AND DEWATERING CLAY. 
The electre-osmose process was next applied to the dewatering 
and purification of clay,!’ for the purpose of transforming a low 
grade and impure material into something approximately in quality 
ball-clay or china-clay. In the older processes the impure clay is 
first made. into a thin slip.with water, the slip is allowed to stand 
until the coarser particles (usually silica) have had time to settle, 
and the fine particles of clay still remaining suspended in the slip 
are removed by gravity settling, filtration or centrifugal separation. 
The settling process is very tedious, and the difficulties of filtering 
or centrifuging are very great. 
Schwerin proposed to hasten and improve the process by de- 
watering the suspended clay by means of cataphoresis. The crude 
clay substance is made into a slip with water in the usual way, the 
kaolin is deflocculated (peptized) by the addition of a little sodium 
hydroxide or other agent such as humus or sodium silicate, and the 
coarser particles are allowed to settle. If the impurities such as 
silica or iron oxide happen to consist of relatively coarse particles 
unadsorbed by the clay itself or even if they are finely divided but 
are not deflocculated (peptized) by the addition agents, the crude 
clay is purified to a certain extent and is usually improved in 
plasticity and firing qualities.. The clay suspension, after settling, is 
pumped into the “osmose” machine where it is dewatered by 
cataphoresis. 
According to Ormandy” the “osmose” machine consists of a semi- 
circular trough, in the center of which a revolving metal drum 
serves as anode and outside of this drum and distant about half an 
inch from it is a cathode of wire netting, surrounding the anode 
drum on the under side. When the suspension is pumped between 
the electrodes, the impurities are said to settle on or under the wire 
cathode, whence they are removed, while clay is deposited on the 
slowly revolving drum in a blanket 45 feet wide and # inch thick, 
containing not more than 20 per cent. of moisture. For other details 
16 Cf. Brit. Pats. 3364, 11626 (1911). 
7 Cf, Brit. Pats, 14369, 23545, 24666 err 10873 (1913); Ulzer: Zeit. angew. 
Chem., 28, (1), 308 (1915). 
18 Brit. Pats. 6993, 6995 (1914). 
19 Cf, Brit, Pats. 10024 (1907) ; 28185 (1911) and others. 
20 Brit. Clayworker, 22, 9 (1913) ; Pott. Gaz., 38, 1162 (1913); 40, 178 (1918). 
Cf. Stoermer : Tonindustrie Zeit., 36, 178 (1915) ; also Hopkins : Brit. Clayworker, 
22, 62 (1913), Cf. Brit. Pats. 725 (1912) ; 3434 (1913), ete. 
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