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cocesses. In'the shorter.modern ' dry prat ess,rs, in the new -type laundry machines. 3. .where accumula- tions of lime soap are to be removed, SHMP is added . to the wash. With synthetic detergents, sodium hexametaphosphate overcomes the effect of hardness derived either from the water or from the goods being washed. - A special grade of "Instant" sodium hexametaphosphate is the most suitable for laundry application. ' Bortict,vashing. In the mechanical washing of bottles. the detergent used is normally caustic soda or one of the sodium silicates. and these introduce precipitation problems with hard waters. Deposition on the working parts of the machine can be prevented by using sodium hexametaphosphate in the detergent bath; 5-10% on the v,. -eight of the detergent is required. This will keep the machine clean and also produce much brighter bottles by improving both the deter- gent action and the rinsing. Where hard water is used, deposition in the warn rinse section may occur, and a threshold concentration of sodium hexametaphosphate (10-15 ppm) should then• be added to the rinse water. Clc ;r,"ng rn Cu ries. Ice Cream Factories, etc. Sodium hexametaphosphate is used in detergents for milk' Innes. churns. etc.. in dairies and for ice-cream maellines. It has a further specialized use in dairies. where it pre•.enis or reduces the build-up of milk•slone: a solution of SHMP is circulated through the p,rsleur; cis at the end of a run and is followed by an alkaline w i5h. Paper industry The dispersing action of sodium hcxamet„phosphale is used in paper coating mixtures. 0.35ron the weight of clay enables the easy and rapid preparation of mobile clay slurries of 60-70% solids content. and other pigments such as titania or calcium carbonate are d,sPersed. The bander, either statch or casein solution is added to the clay slurry and finally the latex is blended into the mix. Sodium hexametaphosphate prevents the deposition of pitch on paper -making machines. The amount required is of the order of 0.05--0.1 % of the weight of pulp, and the SHMP may be added to the hydrapulper before alum is added, or applied as a solution, by sprayrnp. to the parts of the machine where the pitch appears When pulp has been through processes in which alkali is t.sed and then washed in waters of high temporary hardness. calcium carbonate will precipitate on screens and other equipment. A threshold concen- tf3tion (2-5 ppm) of sodium hexametaphosphate in the .ti -ash water will tippreciably reduce this piecipi- taiion. Lime state is also prevented in the soda digestion of esparto grass by the addition of 100-200 ppm sodium hexameiaphosphale. Leather Sodium hexametaphosphate can be used as a tanning agent but its principal industrial application in leather - making is as a pre -tanning agent. SHMP pre -tanning b, -fore vegetable tanning enables goods to be put into relatively strong tan liquors without loss of penetration, and the lime required for the completion of the tanning can be appreciably reduced. Leather produced in this way has increased resistance to the rotting which takes place in industrial atmospheres. Sodium hexametaphosphate pre -tanning before throrne tanning results in fuller finished leathers and grains which can be buffed more deeply without rte, k Of toosen1ng Pllnsphale Glass 696 is frequently used for this purpuse. Defloccuiation Sodium hexametal,,..,sphate will deflocculate sus- pensions of solids in water, and in addition to the paper - coating application, this property is used in slip- cr-sting, sometimes with the addition of an alkali; the arnount of sodium hexametaphosphate required is critical and must be determined by experiment. but one advantage is that the pint -weight of the slip can be.significantly increased. Similarly, in some types of raw cement slurries. SHMP can be used to increase the solids content for any given viscosity. Other interesting applications are in the Precision casting of precious metals and in the stabiliz- ing of soils for the bottoms of reservoirs. Sodium hexametaphosphate is also used in entvlsion r Paints, particularly with rutile pigments; belwaon 0.1 and 0.5% of the weight of the pigment is effective. Other applic2tions ,ire in the the of china clay to 'float the clay from the heavier impurities. In the cleaning of zeolite softeners when their efficiency has . been reduced by insoluble products from the Wool. in clay soil or pigment suspensions for particle site mer.surement. and in oil well drilling muds--t,rh;:r+ PhOsphalo G1Fss 627 his alao found t)pplicclions Fgod Sevor3l SO -Burn pliG phrrlc6 ora Mcil ot r rrtrl¢�1yinV salt, in Ilio pre-Datation of eru.tlot.t Ghi?efa, gnd $001urn tick ainclophorphoiv hog prupertlet ivhsch mrk! it 0110 Of the It11010 important Sodium hexomet8pho6phala it used to ,tip y,cld of prctin Oxtracted from apple pomade 8nd tutus Pulp Tho amount roquuod is usually 2-3% CDIculrilA on the weight of pomata or pulp. A similar application . Is in the manufacture of jams and marmalade, where an additional ,,)dvantage is often obtained In improved clarity of the finished product. For this purpose. quantities of Ivss than 1% calculated on tho fruit pulp, are usually adequate. Sodium hexametaphosphate solutions will soften the skins of peas and beans, and treatment with 0.2% solutions has been applied to these vegetables before canning or freezing. With pickled meats such as hams, the presence of 5% sodium hexametaphosphate in the brine reduces jelly formation when they are cooked in the can, and the harms have improved colour retention after being re- moved from the can. The sequestering power of SHMP is utilized in preventing the clotting of the blood of animals so that a protein -containing serum can be separated by centrifuging. The quantity of S14MP required is about 0.1%. Sodium hexametaphosphate in sausages and similar meat products increases the stability of the fat emulsion, and approximately 0.5% in such products reduces the separation of fat during cooking. Food and BPC grades of sodium hexametaphosphate are available. Miscellaneous Uses Sodium hexametaphosphate as a dispersing agent for iron compounds is applied to the purification of glass - making sands. Molten sodium hexametaphosphate dissolves most metallic oxides. It has been used as a flux with non- ferrous metals and for the cleaning of crucibles. When mixed with soaps, sodium hexametaphosphate improves the lathering power and it has been used extensively for this purpose on the Continent. In Great Britain, the principal use of this kind has been in liquid soaps and shampoos; an important part of the effect sought is the clarification of the liquid, which remains