24 A ANALYTICAL CHEMISTRY

A.H.T. CO. SPECIFICATION

MAGNETIC STIRRING APPARATUS For variable speed stirring action wi th in either closed or open vessels

9235-R. Fig. 1. Showing general stirring in a stoppered

flask.

Fig. 2. Fig. 3. Showing stirring in eleetrometric titrations Showing stirring in a closed system for deter-

with air and moisture excluded. mination of gas volume changes.

MAGNETIC STIRRING APPARATUS, A .H.T . Co. Specification. A compact , quiet-running appara tus which utilizes a rota t ing field of magnetic force to induce variable speed stirring action within either closed or open vessels. Stirring is accomplished by means of a small magnetized bar A or B, sealed in Pyrex glass, which is placed in the liquid to be stirred and which is ro ta ted by magnetic force applied below the container.

Consisting of a permanent bar magnet a t tached to the shaft of an electric motor and mounted in an aluminum housing with flat top 4 % inches diameter and 4J4 inches high. Can be used either on the table or on a support rod, attached by means of a clamp with swivel joint. Any type of vessel of glass, porcelain or non-magnetic metal, can be used, i.e. flasks, beakers, culture dishes, crystallizing dishes, evaporating dishes, test tubes, weighing bottles, etc. A ring-type burner is suitable when stirring at elevated temperatures. Suitable for any stirring opera­tion which involves 1 ml to 1 liter of liquids with viscosities up to that of a 50% glycerol solution. Particularly con­venient for use in closed systems where :

Gas volume changes must be observed, as in hydrogénation experiments;

High vacuum or overpressure should be main­tained;

Moisture and air should be excluded, as in titra­tions involving the use of Karl Fischer reagent;

Gas phase over the surface of the liquid should not be mixed into the solution;

Change in turbulence is required without dis­turbance of heavier phase above stirred por­tion;

Small containers are used, as in microchemical procedures.

923S-R. Stirring Apparatus, Magnetic, A.H.T. Co. Specification, as above described, with one each stirring bars A and B, • Yi inch and 1 Yi inches long respectively, rheostat, 8-ft. connecting cord, and directions for use, but without glass vessel. For 115 volts, 60 cycles, a.c 32.3S

9235-T. Stirring Bars, Magnetized, for replacement in above Stirrer; consisting of half-round permanent magnets sealed in Pyrex glass. Overall dimensions, inches Κ χ Κ x iNÎ 1 H ^ K X ^ E a c h 1.80 1.80

9235-U. Ditto, Plastic Coated. With baked on lustrous black plastic coating which was developed to eliminate accidental breakage possible with glass-enclosed bars. The plastic coating will withstand continuous use in boiling water and has good chemical resistance to acids and alkalies except those with oxidizing properties such as nitric acid, alkaline peroxides, etc. ; also resistant to organic solvents, but an unqualified statement can not be made because of the wide variety of solutions in which they may possibly be used. Overall dimensions, inches % x M x ^ I K x M x H E a c h Π75 U9Ô

More detailed information sent upon request.

ARTHUR H. THOMAS COMPANY R E T A I L — W H O L E S A L E — E X P O R T

LABORATORY APPARATUS AND REAGENTS WEST WASHINGTON SQUARE, PHILADELPHIA 5, PA., U. S. A.

Cable Address "Balance," Philadelphia