Februaet 24, 1922] 



SCIENCE 



215 



and other intermittent types. (7) Limitations 

 and disadvantages. 



Suction filtration: G. D. Dickbt. After a brief 

 outline of the development of suction filtration, 

 there are taken up the four main points of inter- 

 est to filtration operators, viz. : Cake formation, 

 washing, drying, and discharge. Under ' ' Cake 

 Formation, ' ' there is discussed the various fac- 

 tors which modify cake building in suction appa- 

 ratus. Examples are cited as to capacities and 

 rates of fiow of specific materials under varying 

 conditions, which will illustrate the influence 

 that these conditions exert over the deposit of 

 the filter cake. Following the discussion of the 

 filter cake comes that of washing of the cake, 

 which of course is dependent upon the formation 

 of the cake itself, but which can be greatly aided 

 or hindered by the filter operator. The discus- 

 sion of cake drying and discharge is also based 

 primarily upon the cake formation, but allows of 

 many modifications before obtaining the desired 

 results. Next there is given a brief description 

 of the construction and operation of the open 

 tank type of filter, the continuous rotary filter, and 

 the continuous rotary hopper dewaterer, together 

 with the advantages and disadvantages of each 

 type. A number of lantern slides have been pro- 

 vided, so that the discussion of the construction 

 and operation can be illustrated. In conclusion, 

 there is given specific data as to the handling of 

 a number of materials by the three types of 

 apparatus above mentioned. 



Industrial filter media: Aethue Weight. De- 

 fines industrial filtration as the separation of a 

 comparatively large amount of solids from small 

 volumes of liquid, hence small rates of flow are 

 permissible and filter cloths used as contrasted 

 with the municipal filtration where gravel beds 

 are used and conditions are the opposite. Selec- 

 tion of filter fabric depends upon whether for 

 non-corrosive or corrosive liquors. For the latter, 

 wool, metal, asbestos, stone, etc., is used, while 

 for the former, cotton is used. Describes various 

 weaves of cotton and its use. Fabric filtration 

 should be of surface type, and not bed filtration 

 where solids enter interior of the medium as in 

 loose thick duck. Suggest superficial layer of 

 thin muslin to prevent bed action, permitting 

 cake to fall off easily. In certain kinds of filters 

 the cloth porosity must be of definite kind to 

 permit use of back pressure. Cake adheres more 

 strongly to unnapped cloth. Discusses drainage 

 provided under cloths. Precoating cloths should 

 be used where initial filtrate must be clear. 

 Shrinkage and stretch of cloth is considered. 



Mentions incrustation due to lowering pressure 

 and suggests action to be taken. 



The use of filter-eel for industrial filtration 

 processes: G. M. Hicket. Filter-Cel, a porous 

 cellular product, is used as a filter aid, by mixing 

 a small percentage with the liquor prior to filtra- 

 tion, overcoming slimes and giving brilliant fil- 

 trates. In cereal beverage filtration, addition of 

 one fourth pound of Filter-Cel per barrel insures 

 complete removal of j'east cells, gives brilliant 

 product and permits use of modern pressure 

 filters. In crude and refined vegetable oils it 

 aids in the removal of foots, soaps and slimes, 

 giving clearer filtrates that requires less bleach 

 for refining. When mixed with the bleaching 

 agent, it increases the capacity of filter and 

 gives dryer cakes. Apple products and fruit 

 juices are mechanically clarified by filtration 

 with small quantities of Filter-Cel. Soap lyes 

 and fats are clarified using one per cent of 

 Filter-Cel, improving filtration and the quaUtj' of 

 by-products. Catalytic agents from hydrogena- 

 tion processes are completely removed by filtering 

 with Filter-Cel. 



Plate and frame filter presses: G. B. Eice. The 

 filter press includes a large filter area in a small 

 floor space, high pressure can be used, the appa- 

 ratus is simple, unskilled labor only is required 

 for operation, and repairs are quickly made. 

 Considers the plate and frame type the best form 

 of filter press. Describes washing and various 

 combinations used in filter presses. Filter presses 

 can be made of various materials, as iron, for 

 ordinary materials, wood for weak acid liquors, 

 lead for strong sulphuric acid. For wooden 

 plates resinous woods are best, as yellow pine; 

 such wood will stand 25 per cent, cold HCl. Hot 

 solutions tend to destroy the resin, so for that 

 purpose maple or oak is best. Describes opera- 

 tion and storage of wood presses. Discusses filter 

 plate surfaces, closing gears, and filter cloths. 

 For most aqueous solutions, cotton cloths are 

 good, but for strong acid solutions asbestos, wool 

 or camel's hair cloth is suitable. Wire cloths 

 made of monel metal, copper, nickel and bronze 

 can be used. 



The filter press: D. E. Speeet. The filter press 

 is defined as a press employed for holding to- 

 gether the component parts of a filter. The com- 

 ponent parts of the filter consist of plates or 

 plates and frames. The filter press is described 

 by aid of illustrations. Recessed and flush plate 

 and frame operation is defined. Filter plates and 

 frames may be made of various materials to suit 

 the substance handled. This is also true of filter- 



