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WwwSti·* -"0" F r e e A n a l y s i s Kit . . . The S&S Filter Paper Sampler contains a generous assortment of 11 cm circles in a wide selection of grades. The S&S American filter papers represent a distinct advance in the manufacture and treatment of Analytical Filter Papers. The purity and uniformity of S&S papers are far ahead of those found in any European product, and systematic laboratory supervision of S&S production guarantees strict maintenance of this superiority.

Send for your free sampler today. If you have been using another brand of paper, here's your chance to try the finest and compare right in your own laboratory with no obligation. Address Dept. IN.

• Extremely rapid foi filtra­tion of coarse and gelatin­ous precipitates. High wet-strength. Ash per 11 cm cir­cle 0.04 milligram.

For filtration of: Aluminum hydroxide Beryllium hydroxide Bismuth sulphide Cobalt sulphide Copper sulphide Ferric hydraxlde Iron salt of cupferron Iron sulphide Nickel dimethylglyoxlme Nickel hydroxide Rare earth hydroxides Silicic acid (precipitated! Silver sulphide Titanium hydroxide Tungsten-benzldene complex Zinc hydroxide Zirconium salt of cupferron

S & S For highest precision specify

For-.

available at your favorite

?"' s&s 589-1-H

Photograph Courtesy of J the Fleischmann Laboratories, Standard Brands Incorporated

S&S Analytical Filter Papers make possible new standards of precision Today the more precise laboratory techniques you use are made possible by specialized knowledge and a higher stand­ard of measuring tools. S&S research has kept pace—it has met this challenge.

Every year many chemists who were once satisfied with other brands standardize their procedure on S&S Analytical Filter Papers for consistent accuracy lot after lot, large selection of grades, and the confidence that goes with using the finest. And the finest costs no more.

Skilled S&S research chemists developed the exclusive fea­tures that set S&S apart from ordinary nitration products.

• FOR QUANTITATIVE GRADES: Less than 0.007% ash—lower than any filter paper we believe your purchasing agent can buy. 97-98% alpha cellulose content—higher than any other filter paper we have tested.

• FOR ALL GRADES: Standardization for consistent accuracy. Complete physical and chemical uniformity for each grade lot after lot. Selection from a wide range of grades to match more closely the requirements of any given analysis.

Even if you believe you are satisfied with your present filtra­tion products, you owe it to yourself and your work to try S&S Analytical Filter Papers and filtration specialties, and compare. Send for the free S&S Analysis Kit sampler de­scribed on the opposite page. It costs you nothing, and there is no obligation.

We are proud to meet the challenge from chemists who are never satisfied. For we at S&S are never satisfied. Through continued research Carl Schleicher & Schuell Co. will con­tinue to produce what we sincerely believe to be the finest Analytical Filter Paper in the world.

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CARL S C H L E I C H E R & S C H U E L L CO., Keene, New Hampshire

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ψ Suitable for filtration of ' V*

• Thick, rapid, medium re­parse and gelatinous pre­ tention. Ash per 11 cm cir­cipitates. Ash per 11 cm cir­ cle 0.1 milligram. cle 0.055 milligram. For filtration of: f For filtration of: Copper thiocyanate .luminum hydroxide Mercuric oxide leryllium hydroxide Palladium iodide lismuth sulphide Silver arsenate iobalt sulphide Silver chromate Copper sulphide Silver thiocyanate erric hydroxide Zirconium arsenate ron salt of cupferron ron sulphide lickel dimethylglyoxime lickel hydroxide :are earth hydroxides ilicic acid (precipitated; iilver sulphide itanium hydroxide ungsten-benzidene complex inc hydroxide irconium salt of cupferron

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* s&s S&S . ^ S&S 589 i 589 ; . ·'. . , ' * 507

White Ribbon : , ' Blue Ribbon ί .!•*-"

• Will retain moderately fine » Will retain fine precipi­ • Highly retentive. High wet-precipitates. Ash per 11 cm tates. Ash per 11 cm circle strength. Ash per 11 cm cir­circle 0.055 milligram. 0.055 milligram. cle 0.065 milligram.

For filtration of: For filtration of: For filtration of: Ammonium phosplwmolybdate Barium sulphate, prec. from Antlmonlous acid Barium sulphate* cold solution Antimontous sulphate Calcium oxala te* Calcium fluoride Barium chloride from Hydrated manganese oxides Cesium silicotungstate HCL media Lead chromate* Cobaltic hydroxide Barium nitrate from Lead sulphate Germanium sulphide HNOa media Lead sulphide Gold disulphide Sodium chloride from Magnesium ammnniem phosphate Magnesium basic carbonate HCL media Magnesium hydroxide Nickel sulphide Strontium nitrate from Mercuric sulphide Potassium p-dipicrylamine HNO3 media Rare earth alkali doubla sulphates Potassium uranate Sil ica, as in acid insoluble Silver chloride

determinat ions Silver bromide Tin sulphide, stannous Strontium sulphate Tungstic acid Tin sulphide, stannic Uranyl ammonium phosphate Zinc ammonium phosphate Zinc sulphide, from formic acid media Prec. from hot solution

ANALYTICAL FILTER PAPERS laboratory supply house

Unretouched section photographs of S&S 11 cm circles magnified VA times. All filter papers pictured for use in quantitative analysis.

All papers except S&S 589-1-H are extensively used in chromatography and electrophoresis (available in sheets or strips).