INDUSTRIAL A N D ENGINEERING CHEXISTRY
July, 1929
703
Solubility of Metals in Milk' G . N. Quam L O N G ISLAKDUSIVERSITY, BROOKLYS, S . Y.
U R I S G the past few years many new metals have come to more or less prominence in the dairy industry. Some have been found to possess very favorable properties, while others have received only temporary consideration in the manufacturing of dairy equipment. The effect of certain metals, such as iron and copper, on the quality of dairy products has received much attention (IO,3, 7 , 4, 6 , 2, 6).* The question of corrosion is an old one, but its application to milk, in particular, has been studied comparatively little. The solubility of copper in milk (9) has been found to vary in a very definite may with temperature changes The author's purpose in presenting the data herein is to show the comparison of solubilities of several metals in raw, whole, sweet cow's milk. I n the work reported here, metals of the purest grade obtainable Twre employed. The steel was an 18 per cent chromium steel. The methods of determining the solubility of the metals in milk were in general like those previously reported by the author and his co-workers (9).
D
Procedure
Samples of each metal were cut into strips 7 . 5 X 4 cm. and highly polished. Each strip was folded along the long axis and crimped to insure complete and uniform exposure to the milk. The metal was prepared for each solubility determination by scouring with powdered kaolin, washing in water, rinsing free of water in alcohol, and finally rinsing in ether. After drying for about 1 minute a t 60" C., the strips were placed in desiccators for 15 minutes and weighed. The weighed strips, twelve in a set, were placed in glass tubes containing 50 cc. of raw milk. The set of twelve tubes equipped with breathing pores was placed in a floating agitator (8)and kept in uniform motion in a water thermostat a t the given temperature. The speed of the motor was so regulated that the floating agitator was rocked a t the rate of 46 strokes per minute through a 30-degree angle, this making quite constant the flow of milk over the metal surface. At the end of the 30-minute interval the milk was quickly removed and the metal was transferred directly into running cold water. The metal strips were then prepared for weighing as described above, except that care was taken to remove any loose corrosion products with a cotton swab. The loss in weight was taken as the solubility of the metal per given area. I n addition to the above direct method for determining solubilities, chemical methods were employed for several metals. For such determinations the milk from each tube was ashed and the metal in solution determined in the ash. For nickel the a-benzildioxime method was modified for the work with milk; for steel, iron was determined by the thiocyanate colorimetric method and chromium was determined by a modification of the diphenyl carbazide method; and for copper the ethyl xanthate method was employed. Results
Table I indicates the solubility of each metal in terms of milligram loss per square decimeter surface exposed a t different temperatures. Each value represents the average of eight to twenty-four determinations. The curves in Figure 1 indicate graphically the data in Table I. The average of the losses for aluminum, tin, and I
Received March 25, 1929
* Italic numbers in parenthesis refer t o literature cited at end of article.
steel a t temperatures from 25' to 75' C. were so slight that all were well within the limits of error for the methods of experimentation and were therefore considered negligible. In Figure 1 it was obviously necessary to superimpose several points having to do with the losses of aluminum, tin, and steel. in Weight of Metal per Square Decimeter Exposed to Milk for 30 M i n u t e s TEMPERSTEEL ATURE S-ICKEL TIN (Cr) ALUMINUM ZINC COPPER c. Mg. X g Mg Mg. M g Mg. 20 0.86 0 0 30 .. 0'.2'32 0:iis 1.22 0
Table I-Loss
40 45 50 55 60 6% 8 65 70 75
...
3' 442
...
4.31
0
5.85 ,..
0
, . .
0 0
...
...
80
6.54
85
5 17
90
3.442
95 100
1.22
...
...
... ... ,
I
1: 333 1.462 1.,582
.
..
1.78
...
1.806
0
...
1.546
1.892
.,,
1.961
0
Gain 0.174
1.03
Gain 0.129 Gain 0.1788
...
Gain 0.516
1'.i46
6'
...
Gain 0.378
0.516 0.671 0.860 1.032 1.118
...
1.03
0 0
,..
6 54
0.7i4
6' 6'
, . .
...
...
1.788
...
1.3i6
The curves for copper, nickel, and zinc are quite similar to those reported by Frazer, Ackerman, and Sands ( I ) , who found a break a t 70" C. in their curve for corrosion of monel metal in aerated 5 per cent solution of sulfuric acid. The break in the curve is probably due to the change in solubility of oxygen a t that temperature. Speller (11) reports that the corrosion rate of iron in natural water reaches a maximum a t 80' C. and then decreases a t higher temperatures owing to rapidly decreasing solubility of oxygen. The break in the oxygen solubility curve a t 70" C. is quite pronounced and at 100" C. decreases to such a small value that the oxygen content a t that temperature plays but a small part.
0 n-Zp
___ r e r n p oc
- x-
-fa--*---
sp
5.0
6?
0-
3.0
---_.I_ I _ -
--
-0 -.az
=--- -*---- - 0.-
70
90
~
I
..jj
9 0 _ _ , ~lop
Aluminum and tin are both very inactive in milk up to about 70" C. Above this temperature increise in weight is no doubt due t o the development of a durable corrosion film under the conditions of the experiment. The special steel (chromium) was found to be the most satisfactory metal of all. The surface remained bright throughout the tests. I n a very few instances microscopic rust spots could be detected on strips that had been poorly polished.
704
IXDCSTRIAL AND ENGINEERING CHEMISTRY
It is the oDinion of the author that if the surface could be
(3) Guthrie, New York Agr. Expt. Sta., Bull. 873 (1916).
Quam, IND. Ewc. CHEW, 20, 908 (1928). Quam, Soloman, and Hellwig, I b i d . , 20, 030 (1928). (10) Seligman, Proc. World’s Dairy Congress, Vol. 11, p. 12tn W). (11) Speller, “Corrosion-Causes and Prevention,” p. 144 (1926).
(8)
L i t e r a t u r e Cited (1) Frazer, Ackerman. and Sands, IND. EXG.CHEY..19, 333 (1927). Golding and Feilman, J . SOC.Chem. I n d . , 24, 1285 (1905).
(2)
V d 21, No. 7
(9)
AMERICAN CONTEMPORARIES Maximilian Toch
M
AXIMILIAN TOCH was born in New York sixty-five and microchemistry. These courses he studied in the late afteryears ago, the son of a revolutionist of 1848 who came noons and evenings. here from Bohemia a t the time that Carl Schurz and Ever since the early days with Prof. John W. Draper he has many another of their fellow aspirants t o freedom landed on our been interested in photography and he is today one of nine shores to escape the wrath of the several autocracies against American Fellows of the Royal Photographic Society of London. which they had rebelled. The older Toch His picture of “London Fog” is the single established himself as an importer and dealer example of amateur photography reproduced in paints and pigments, and from small bein the forthcoming edition of the Encycloginnings he prospered. pedia Brittanica. When Maximilian was fourteen years old His reputation as an authority on the he had already completed one year a t the authenticity of paintings by old masters is College of the City of New York. He world-wide. Leading dealers both here and wanted to study chemistry and his father abroad know him, and there are those who took him t o the Columbia School of Mines entertain a wholesome fear of him. During t o consult Professor Chandler in the hope the Great War he developed the Toch of registering for study there. Professor system of camouflage, and he had charge of the color work on all the United States fortiChandler looked a t the boy, who was small for his age, shook his head, and said he fications on the Atlantic Coast as well as that on one-fifth of the ships in the service of could not take children in his course but this country. that in a couple of years he would be welTogether with brother Henry he built in come. I t was a sore blow, but on leaving Tennessee the largest barium reduction plant the lad exclaimed, “Professor, in a couple in the world. After they had it established of years I shall be almost a chemist.” They as a going concern in full operation, they grew t o be warm friends in after life and sold it to the New Jersey Zinc Company. Chandler always regretted that he had not He continues as head of research and promade an exception for this particular youth. duction of Toch Brothers and the Standard Then father and son went down to New Varnish Works. York University, on Washington Square, and A t one time he held the chair of industrial saw old Prof. John W. Draper. He immeMaxirnilian Toch chemistry a t Cooper Union and he retains diately accepted the boy, who proved to be the post of professor of the chemistry of his last student, and before the end of a year young Toch had become Draper’s assistant. Then the old artistic painting in the National Academy of Design. The Unigentleman died and was succeeded by his son, Henry W. Draper, versity of China invited him to go to Peking and teach them the chemistry of Chinese drying oils. For this he was made who continued Toch as his assistant until he died a couple of years later. Then, a t the age of seventeen and still an under- honorary professor a t the Peking Technical College and the graduate, Max was made an instructor in chemistry. A t the same university conferred on him the honorary degree of doctor of time from 3 to 7 o’clock daily he attended the law school of New science. Only two Americans have been thus honored-Prof. York University, attaining the degrees of B.S. and LL.B. on the John Dewey with Ph.D. and Prof. Maximilian Toch with Sc.D. He has written several books on paints and painting which same day and at the age of eighteen. He was later admitted to are standard. He is ex-president of The Chemists’ Club of the bar and he has practiced in patent cases. On graduation he was rather exhausted from the intensity New York and is member of a number of others, including the of his work and his mother took him to Germany for a season. Cosmos Club at Washington. He is a member of many learned societies, is happily married, and has four daughters, all of whom Weariness did not prevent him from taking in lectures by Ostwald in Leipzig, Witte in Charlottenburg, and others, whenever he are also happily married. He does not drink liquor but he does smoke, and he accomplishes the work of a dozen men without had the chance. Returning to America, his brother Henry and he took over appearing t o be rushed or even busy over it. He loves t o wander their father’s business, and under Maximilian they began the in the pleasant gardens of the mind and discuss almost any submanufacture of paints that has since grown into the great es- ject that is not offensive. He hates smut. He is vastly well informed but does not boast of it. And he is an artist in friendtablishment of Toch Brothers. But nothing could quench his thirst for scientific knowledge. Already in business, he regis- ship because the better one knows him the more one is sure t o ELLWOOD HENDRICK like him. tered for graduate study a t Columbia and pursued bacteriology
