June, 1916
T H E J O U R N A L O F I N D U S T R I A L A N D E N GI iV E E RI iVG C H E M I S T R Y
RELATIVE TOXICITY OF SUBSTANCES FOUND IN FOODS By ALFREDN. COOKAND SYLVANNA ELLIOTT
503
fishes, each, were used in making this investigation a n d t h e results recorded here are averages of a very large number of individual experiments. Received February 7, 1916 I n order t o have some standard, t h a t particular This investigation was undertaken with t h e hope t h a t strength of solution of benzoate of soda which would some useful d a t a might be accumulated t h a t would cause t h e death of a frog or fish in from 5 t o 7 days help solve t h e question of chemically preserved foods was called (‘one,” a n d t h e various solution strengths a n d their effects upon t h e h u m a n system. Since of t h e other chemical substances experimented with our laws a n d ethical standards forbid t h a t experi- divided into ( ( o n e ” was taken as t h e degree of toxicity ments of t h e nature t o be described should be macle compared with t h a t of sodium benzoate. upon human beings, t h e only available method is t o According t o t h e above tabulation (frog s t a n d a r d ) , experiment upon animals of lower rank a n d make sodium benzoate, sodium chloride a n d borax all have deductions from t h e results obtained. about t h e same relative toxicity. Sodium chloride , I t has been indicated a number of times t h a t there is used in foods with impunity, sodium benzoate is are instances in which t h e food of one animal is poison allowed in foods if its presence a n d t h e per cent thereof for another, for example, copperas is poison for a is declared on t h e label, while borax is debarred from human being b u t m a y be eaten almost with impunity use i n foods in this country. Sodium salicylate, by a hog; saltpeter m a y be taken into t h e human sysglucose a n d alcohol all have about t h e same relative t e m in considerable q u a n t i t y without deleterious toxicity, yef sodium salicylate is not allowed in foods effects b u t i t is poison t o a sheep. Notwithstanding these occasional instances, there has been a differ- on account of its deleterious effects upon t h e health, while glucose is a common article of food. Under t h e ence of opinion with regard t o t h e value of such exfood laws alcohol is not debarred from foods on acperiments, b u t m a n y men high in authority have count of its toxic effects. Rochelle salts occurring in considered t h e m valuable. Because of t h e difficulty of caring for many differ- baking powder residues, potassium oxalate occurring e n t kinds of animals in t h e laboratory, our experiments in pie plant, citric acid occurring in lemons a n d were confined mostly to gold fish a n d frogs. The other fruits, cane sugar, one of t h e most common frogs averaged about z j g. in weight a n d t h e gold articles of food, malic acid occurring in apples and other fruits, a n d tartaric acid occurring in grapes fishes were from 3 t o 4 in. long. The frogs, of fairly uniform size, were kept in shal- are all more toxic t o frogs t h a n sodium salicylate low pans which were carefully enameled t o prevent which is properly excluded from human foods under a n y chemical action between t h e substances in solu- t h e terms of t h e federal law. I t will be noted t h a t tion a n d t h e container. T h e frogs were kept partly sodium sulfite, which is not a legitimate constituent immersed in t h e respective solutions. The gold fishes of food, is much less toxic t o frogs t h a n many of t h e were of fairly uniform size a n d were kept in liter beak- most common constituents of our daily food. Cane ers. Both frogs a n d fishes were kept in one liter of sugar is about three times as toxic t o frogs as glucose, t h e respective solutions which were frequently renewed a n d tartaric a n d acetic acids are more toxic t h a n sact o prevent a n y error by concentration or absorption. charine. I n case of fishes, as is well known, sodium chloride ,411 solutions were prepared with distilled water. is not toxic. Cane sugar, Rochelle salts, glucose, COMPARATIVE RESULTS alcohol a n d potassium oxalate are all less toxic t h a n FROGS FISHES sodium benzoate. I n case of frogs, however, t h e y are Potassium Nitrite.. . . . . . . . 0 . 2 5 Sodium Chloride.. ... N o t toxic Sodium Sulfite.. . . . . . . . . . . 0.7 Cane sugar.. . . . . . . . . 0.004 all more.toxic t h a n sodium benzoate, a n d some of Sodium Benzoate. . . . . . . . . 1.0 Rochelle Salts.. . . . . . 0 . 0 5 7 1. 0 Borax. . . . . . . . . . . . . . . . . . t h e m much more so. Citric acid, acetic acid, malic 1.1 Sodium Chloride.. . . . . . . . . Glucose. ............ 0 . 1 1 4 2.0 Sodium Salicylate, . . . . . . . . Alcohol. . . . . . . . . . . . . 0 . 1 6 acid, a n d tartaric acid, all of which occur in fruits, Glucose.. . . . . . . . . . . . . . . . . 2 . 0 Potassium Oxalate. . . 0 . 4 2 8 Alcohol. . . . . . . . . . . . . . . . . . 2 . 0 some of t h e m in large quantities, are all more toxic Sodium Benzoate.. . . 1 . 0 t o fishes t h a n are either caffein or saccharine, whereas Caffein.. . . . . . . . . . . . 2 . 8 0 Saccharin,. . . . . . . . . . 2 . 8 5 in case of frogs citric and malic acids are less toxic Citric Acid.. . . . . . . . . 6 . 0 0 Malic Acid. . t h a n saccharine. I t is interesting t o note t h a t malic, Saccharin. . . Alum... . . . . . . . . . . . . 8.00 Benzoic Acid tartaric a n d benzoic acids are all more toxic t o fishes Acetic A c i d . . . . . . . . . 8 . 5 7 Carbolic Acid. . . . . . . 10.7 t h a n carbolic acid, whereas in case of frogs t h e reMalic Acid. . . . . . . . . . 1 2 . 8 verse is true. I n both cases alum seems t o be much Tartaric A c i d . . . . . . . . 14.0 Guaiacol. . . . . . . Benzoic A c i d . . . . . . . . 2 0 . 0 more toxic t h a n sodium benzoate or saccharine. 9-Cresol.. . . . . . . . . . . 2 4 . 0 Carbolic Acid.. ... m-Cresol.. . . . . . . . . . . 2 4 , O m-Cresol ......... ,ittention should be called t o one point which seems +-Cresol.. ................ 3 0 0 . 0 o-Cresol.. . . . . . . . . . . 3 0 . 0 very significant. I n case of both frogs a n d fishes it An a t t e m p t was made t o determine t h e strength of a will be noted t h a t t h e free benzoic acid is much more given solution in which a frog or a fish would live not toxic t h a n sodium benzoate. This is in accordance less t h a n five nor more t h a n seven days, b u t t h e fac- with our general knowledge on t h e subject with retor of individual resistance, of course, interfered with gard t o t h e toxicity of t h e stronger acids a n d their a high degree of mathematical exactness, a n d t h e salts. For example, hydrochloric a n d nitric acids necessity of using a n average of a large number of are very much more toxic t h a n their ordinary metallic results is very apparent. Several hundred frogs a n d salts. I t will be observed also t h a t in case of both
T H E J O LTRiVAL O F IL$TDLTSTRI.4L AA7D EhiGI;\rEERINC CHEA41STRY
5 04
frogs a n d fishes Tartaric acid is much more toxic t h a n Rochelle salts. So far as the writer is aware, no series of systematic observations so extensive as those here recorded have ever been made. Only isolated experiments seem t o have been conducted with no efforts a t comparatil-e results. Our conclusions from these experiments were far different from our expectations in t h e beginning, which opinions mere based on opinions of some eminent men in the field of investigation. The Referee Board of Consulting Scientific Experts, for example, laid great stress on t h e fact t h a t sodium benzoate is not toxic t o frogs as comparative evidence in drawing conclusions as t o its toxicity t o men. Such experiments as these in t h e past have been often relied on a s evidence in court as t o t h e poisonous character of substances used in foods. b u t after studying the d a t a we have accumulated somewhat carefully, the writers have come t o t h e conclusion t h a t experiments of this nature, a t least upon animals so distantly related t o man, do not furnish conclusii-e evidence of the effects of such substances upon the human system. L NIVERSITY OF SOUTH DAKOTA VERMILLION.S D
THE GRAVIMETRIC DETERMINATION OF REDUCING SUGARS IN CANE PRODUCTS B y GEORGEP. M E A D EAND JOSEPH B. HARRIS Received February 10, 1916
The reference books devoted t o sugar analysis all describe the determination of reducing sugars in considerable detail. The detail concerns t h e method of heating, t h e time of boiling, the filtration of t h e cuprous oxide, t h e determination of t h e copper b y a n y of sex-era1 methods. and t h e calculation of results. On t h e other hand, t h e preparation of t h e solution, t h e clarification and removal of excess lead are, as a rule, referred t o very briefly and in the broadest terms: “Clarified if necessary with a minimum of neutral lead acetate solution-deleading b y means of sodium carbonate, sodium sulfate, potassium oxalate or other means.”’ li I n case clarification with lead acetate is used, the excess of lead must be removed; this may be done b y t h e addition of a soluble carbonate, sulfate or oxalate.”z T h e present investigation was undertaken a t t h e suggestion of G. L. Spencer, Chief Chemist of T h e Cuban-American Sugar Company, and carried on under his general direction. The work extended over a period of eighteen months. Failure t o obtain concordant figures from several laboratories on exchange samples of final molasses called attention t o t h e necessity for t h e revision of t h e routine method. The method of precipitation and the determination of t h e copper were under strict specifications in all the laboratories t o which the exchange sample had been sent. so the indication mas t h a t the source of difference lay in t h e preparation of the solution for analysis. 1
I
Browne’s “Handbook of Sugar Analysis,” p. 443. Deerr’s “Cane Sugar,” p. 468.
Vol. 8 , l 7 o . 6
G E N E R A L IIETHOD
Throughout the investigation t h e Meissl and Hiller method was employed; 50 cc. of t h e solution for analysis and j o cc. of mixed Fehling’s solution were heated in a beaker t o the boiling point for 1 minutes, and maintained a t gentle ebullition exactly 2 minutes. X gasoline burner mas the source of heat. At the e n d of t h e boiling period I O O cc. of cold, recently boiled distilled water were added and t h e solution filtered in a n alundum crucible or fused silica Gooch crucible. T h e cuprous oxide was always burned t o cupric oxide in an electric muffle a t full red heat for a t least 3 0 min. Other methods of determining the copper were employed a t times as well, and comparisons are tabulated where this was done. L E A D A C E T A T E soLnTIos-The Iead solution employed was a j6O Brix solution of normal lead acetate, acidified faintly with acetic acid. S A M P L E - F O ~ the first part of t h e work a sample of final molasses of the following analysis was used: Brix 8 7 . 2 , polarization 3 6 . 7 , Clerget number 1 2 . 4 3 , reducing sugars about 1 1 . 0 0 per cent. This was warmed, mixed thoroughly and stored in an air-tight jar. Weights of this molasses were taken so t h a t j o cc. of solution contained I gram of molasses A X O U S T O F L E A D T O B E USED-TO rarious portions of solution containing I gram of molasses t o j o cc. u-ere added lead acetate solution-o. I . 0 . 2 , 0 . 3 , 0 . 4 , etc., cc., respectively, per gram of molasses. The filtrates were tested with HCI. The filtrate from the portion using 0 .j cc. lead solution shoTved a slight precipitate. The portion containing 0 . I cc. lead solution filtered slowly, t h e filtrate showing a precipitate with hydrogen sulfide. This covered the range in which might be included “sufficient lead t o clarify,” as 0 . I cc. showed an excess of lead in t h e filtrate (with hydrogen sulfide). and 0 . j cc. was necessary t o precipitate everything which could be brought down completely with normal lead acetate. The first series of tests was made using 0 . j cc. lead solution per gram of molasses. COUPARISOX
OF
ORDIXARY
DELEADIXG
AGEXTS
AKD
V A R Y I K G AMOUKTS O F LEAD
TABLE I-UTEIGHTS OF CUO F R O M 1 GRAMOF ?*fOLASSES 0.5 cc. Lead Solution per G r a m of Molasses, Deleaded, with Various Deleading Agents in Solutions, t h e Amount Indicated Being per Gram of Molasses Sodium carbonate Potassium oxalate Sodium sulfate 2 cc. 10% solution 2 cc. l0Yc solution 2 cc. saturated solution 0.2517 0.2547 0,2646 0,2500 0 2547 0.264; 0.2549 0.2561 0 2649 0.2525 0 2644 0 2515 0 2605 0 2521 0.2616 I _ _
__
__
A v . , 0.2534 0.2634 0.2522 Spaces separate determinations made on different weighings
T h e carbonate and sulfate check, but t h e oxalate gives weights of CuO I O mg higher. As the deleading agents all gave considerable precipitates with 0 . j cc. of lead solution, a second set of tests mas made using 0 . z j cc. of lead solution per gram, one-half t h e amount used above. This was about the minimum of lead giving a rapid filtration. As sodium sulfate did not form any precipitate with this smaller
