INDUSTRIAL A N D ENGINEERING CHEMISTRY
September, 1927
1005
Pasteurized M i l k PROCESS4 Max. Av.
USUAL
Min. T a b l e I-Copper PLANT 1
Found in Fruit Products P. p . m.
Strawberry preserves Blackberry preserves Cherry preserves Apple butter Chile sauce Ketchup
PLANT 2
C u r r a n t jelly Raspberry jelly Kaspberry preserves Peach preserves Strawberry preserves Blackberry preserves Apple butter Grape j a m Chile sauce Ketchup
4 4 3 3 7 8
PLANT 3
P. P . m.
Plum jelly Strawberry jelly Raspberry jelly Raspberry preserves Apple butter Chile sauce
-A
45 110 18
PLANT 4
2 7
Raspberry jelly Raspberry preserves Blackberry preserves Cherry preserves Strawberry preserves Apricot preserves Plum preserves Peach preserves Pineapple preserves
6 10 3 24 4 8 12
4
4 9 11 6 4
Apple cider concentrate ( a ) Apple pulp ( b ) Finished apple butter (1a:lOb) Tomato pulp Same after cooking approx. 1 . 5 hours
Raw T o p of cooler Bottled
P.9.m. 0.40 0.45 0.48
P.0.m. 0.60 0.70 0.72 Raw M i l k
P.p.m. 0.47 0.60 0.62
ELBCTROPURE PROCESSb
P.9.m. 0.45 0.60
0.52
Average of five samples delivered b y farmers to receiving station: Kaw , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . O . 43 p. p. m. Same after screening., , . . , . ,. , . . . . , , , . , , , , , . , . . , . . O . 45 p. p. m. Average of three small batches screened after copper screens had stood e r posed to air for about 5 minutes between loads. . . . . . . . , . O . 97 p. p. m.
Condensed M i l k Average of three samples of skimmed milk, condensed to 36 per cent total solids in copper vacuum pans. , . . . , , , , , . . . . , , . , , , . . 3 . 7 p. p. m. 0 -4verage of duplicate tests a t five plants, pasteurizing 30 minutes at 1 4 2 O F. in tin-lined vats and using tin-lined copper piping. b Average of two plants, heating to 162’ F. between carbon electrodes.
. ..
3
TESTS D C R I N G P R E P A R A T I O I7 I N COPPER EQUIPMENT
Plant A P. b . m.
C o n t e n t of Milk
T a b l e 11-Copper
the most important. Differences in acidity may also have had a minor influence.
Plant B I’. b. m.
6
17
Eating a hundred grams per day of such products as those from Plant 3 would alone cause one to exceed the limit of copper previously suggested, without considering 1 hat which n-ould normally be supplied in natural foods.* Incidentally, this brand was the cheapest of the group and that of Plant 1 the most expensive. hIIm-The results of the tests on milk (Table 11)correspond closely with those obtained by Supplee and Bellis. The smaller amount of copper getting into the milk during Electropure pasteurization is probably due to the shorter exposure to metallic equipment while hot, as the extent and condition of the piping was similar. The copper content of milk is especially important in its effect upon flavor. McHargue, J . Agr. Research, 30, 193 (1925); Guermont, Compt rend, 111, 196 (1920); Maquenne and Demoussy. I b z d , 170, 87 (1920). 8
C A R B ~ S A T E D BEVERAGES-T~~ tests on carbonated beverages (Table 111) show that normally very lit’tle copper is dissolved. I n general practice the first few bottles of each run are discarded to avoid mixing of sirups, so that those which contain appreciable amounts of dissolved metal are automatically discarded. Since such beverages are always prepared cold, with little access of air, and are exposed t’o the metal for only a short time, little contamination wibh copper would be expected in normal plant practice. T a b l e 111-Copper
Lemon s o l a Cream soda Cherry soda Oranze soda Grape soda Coca Cola Root beer
F o u n d in C a r b o n a t e d Beverages P r o d u c e d i n Brass E q u i p m e n t Plant I Plant I1
P . p . m. P. p . m. 0.5 First bottle of lemon soda a t be0.3 ginning of run 0.8 0.5 0.4 F i f t h bottle 0.6 0.5 0.6 After 20 minutes’ continuous run 0.5 0.5
P. p . m. 0.9 0.7 0.6
Acknowledgment
The authors wish to acknowledge the assistance given by
P. A. Zook and TV. H. Busch in supplying some of the materials for analysis.
Adhesives and Adhesion‘ Mechanical Properties of Films of Adhesives By J. W. McBain and W. B. Lee UNIVERSITY OF BRISTOL,ENGLAND, A N D STANFORD UNIVERSITY, CALIF.
REVIOUS papers have
P
demonstrated the significance of the determination of tensile strength of adhesives and have provided a ready routine method for The presthis purpose.’ t o ent paper indicates the importance of the study of other mechanical properties of films of adhesives, such as elasticity, brittleness, flexibility, ductility (in general “deforma b i l i t y ” ) , relaxation, and
Typical and significant data are presented for the mechanical properties of a number of adhesives and adhesives with added substances. The observations emphasize the essential importance of ”deformability” of an adhesive. Both this and tensile strength depend upon such factors as degree of humidity. The brittleness of an adhesive film may be greatly increased or entirely eliminated by appropriate additions. The strongest adhesive film here measured is isinglass with a tensile strength of 8 tons to the square inch in an atmosphere of 0 per cent humidity; the weakest are the gums and sodium silicates with a tensile strength of only a few hundred pounds per square inch.
Received M a y 9 , 1927. Investigation undertaken for the A4dhesives Research Committee of t h e Department of Scientific a n d Industrial Research, Great Britain, and published b y permission of this Department.
*
McBain and Hopkins, J . Phys. Chem., 29, 197 (1925).
6
Second Report of Adhesives Research Committee, 1926, p. 34. McBain and Lee, J . so
