the ANALYST'S column L.T. Hallett, Editor
SPEEDY ·
SERVICEABLE ·
STURDY ·
TWO-STAGE DUO-SEAL VACUUM PUMP Especially Adapted for Lecture Demonstrations, Physics and Chemical Laboratories GUARANTEED VACUUM
V I / " E LEAR.NEli R E C E N T L Y T H A T t h e
National Bureau of Standards, in cooperation with the American Leather Chemists' Association, has developed a method to determine the amount of lignosulfonates pres ent in tanning materials. The method is based on the precipitation of lignosulfonates with cinchonine. Tests made in six laboratories with 24 contrasting samples show that the method is generally applicable, that it is simple and fast, and that it requires no special equipment. 1 Lignosulfonates, obtained as waste products in the manufacture of cellulose from wood, are often used in the tanning of leather. Pos sessing no tanning properties of their own, they act as auxiliary agents and as extenders for more costly vegetable tannins. However, large amounts of lignosulfonates in tanning materials become harmful adulterants, and a method for their control has long been sought. Estimating the amount of ligno sulfonates in the presence of vege table tannins is difficult as both mix tures have complex organic mole cules with similar structures and functional groups. Lignosulfonates are characterized by their "methoxyl value"—i.e., the percentage of methoxyl groups they contain. But vegetable tannins may also contain methoxyl groups, so that this method of estimation is feasible only when the nature of the vege table tannins is known. The method of precipitation of lig nosulfonates with cinchonine was first suggested by Appelius and Schmidt. 2 According to their find ings, lignosulfonates form insoluble compounds when a cinchonine rea gent is added to a solution of vegeDahl, Sverre, Mandel, John, J. Am. Leather Chemists' Assoc, 52, 184 (1957). ! Appelius, W., Schmidt, R., Collegium, 1914, 597, 706.
EFFICIENT
0.1 Micron (.0001 mm HgJ OPERATING SPEED 450 R.P.M. PAT.
FREE AIR CAPACITY 21 Liters Per Min No
VISIBLE OIL LEVEL
2,337,849 1 / 3 H.P. M o t o r 1 7 2 5 RPM
No Splash —• No O i l Back-up
Belt Tightening Provision
• QUIET • COMPACT
Extra S u p p l y o f Duo-Seal O i l
N o . 1400-B DUO-SEAL V A C U U M PUMP (Motor Driven)
Complete with Motor
P R I C E $133.00
Totally Enclosed Bell G u a r d for 1 4 0 0 Β Pump $ 1 5 . 0 0
W. M. WELCH SCIENTIFIC COMPANY DIVISION OF W. M. WELCH MANUFACTURING COMPANY
ΕSTABLISHED
1880
1515 SEDGWICK STREET, DEPT. A - 1 , C H I C A G O 1 0 , I L L I N O I S , U.S.A. Manufacturers of Scientific Instruments and Laboratory Apparatus
HEVI-DUTY "MULTIPLE UNIT' TUBE FURNACES
1 "
Two Maximum Temperature Ranges to choose from 1850°F and 2200°F
HINGED or SOLID TYPE!
In each range long life "Multiple Unit" brand heating units offer fast heat up be cause the heat is radiated directly into the heating chamber. The heating length may be divided for zone temperature control. These Hevi-Duty Furnaces are available in a wide range of diameters and lengths. Many sizes are in stock. Special sizes made to your specifications for horizontal or vertical operation, up to 1 2 " diameters.
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Λ" '° Len
9>hs
See your Laboratory Supply Dealer or write for Bulletin Lab. 5 5 2
HEVI-DUTY LABORATORY FURNACES
ELECTRIC MULTIPLE UNI1
COMPANY ELECTRIC EXCLUSIVELY
MILWAUKEE 1, WISCONSIN For further information, circle number 57 A-2 on Readers' Service Card, nage 87 A V O L . 2 9 , N O . 1 0 , OCTOBER 1 9 5 7
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