JOURNAL OF PHYSICAL SCIENCE (WITH WHICH IS INCORPORATED THE "CHEMICAL GAZETTE"). Established in the Year 1859. Published Weekly. Annual Subscription, free by post 1 Entered at the New York Post Office as Second Class Mail Matter. Friday, May 2, 1919 CONTENTS. PAGE The Analysis of Sausages, Meat Pastes, and Army Rations, by 205 206 208 ...... 212 .... 214 ...... 215 ....... 215 216 A Registered as PRICE 4d. a Newspaper. POST FREE 48. ssistant Chemist (22), Higher Certificate InOrganic Chemistry, Board of Education,6 years' experience in Steel Works Laboratory, other qualifications, good references, desires Position in Steel Works or Engineering Works. Would consider other vacancies. Address, X. Z., CHEMICAL NEWS Office, 16, Newcastle Street, Farringdon Street, London, E.C.4. Chemist, with four years' training at Finsbury Technical College, having taken active service immediately upon completion of cours-, is now demobilised and seeks Engagement. -Address, A. k. G., 21, Chestnut Road, West Norwood, S.E. Demobilised Soldier (21), Inter. B.Sc. (Lond.), CAPPER PASS & SON, Lim., Secondary School, desires Position in Works Laboratory, preferably BEDMINSTER SMELTING WORKS BRISTOL, are buyers of LEAD ASHES, SULPHATE OF LEAD, two years' experience as Laboratory Demonstrator at a in Midlands or London district.- Address, A. E. B., 13, Midland Road, Rushden, Northants. Enterprising Assistant Chemist (21) desires a Position in a Laboratory or Works. Formerly Assistant TIN, COPPER, LEAD, and ANTIMONY. Metallurgical Chemist (33) desires change. No. 3 S.B. (Code word "Accent "). BEAM, 6 inches; CAPACITY, 500 grms. SENSITIVITY, 0.1 mgrm. An BOROUGH OF PORTSMOUTH. n ASSISTANT, with a knowledge of Food and Drug Analysis, is required in the Public Analyst's Department. Salary at the rate of £150 per annum, terminable by three months' notice on either side. Applications, with copies of not more han three recent testimonials, should be sent to me at the Town Hall, Portsmouth, on or before MAY 12th next. G. HAMMOND ETHERTON, Town Hall, Portsmouth, April 25, 1919. Town Clerk. PATENTS AND DESIGNS ACTS, 1907-1914. MANUFACTURE OF PHENOLIC CONDENSATION PRODUCTS. The Address-BOULT, WADE, and TENNANT, STRONTIUM SULPHATE (Average sp. gr. 3.95). L. OERTLING, TURNMILL STREET, THE BRISTOL MINERAL and LAND LONDON E.C. 1. COMPANY, LTD., are Owners of large deposits, and invite enquiries. Address, Carlton Chambers, Baldwin Street, Bristol, England. Telegraphic address" Beetroot," Bristol. Telephone No. 38, Bristol. CHEMICAL NEWS, Analysis of Sausages, Meat Pastes, and Army Rations May 2, 1919 THE CHEMICAL NEWS VOL. CXVIII., No. 3081. 205 allowed for water. The ash consists mainly of salt, though in 12 out of 60 samples analysed boric acid was also present, but in small amounts. The total ash varied from 12 to 3 per cent, with an average of 2 per cent. The results obtained from the five following samples may be of interest; they are selected (Table I.) as showing THE ANALYSIS OF SAUSAGES, MEAT PASTES, mainly the extremes of each ingredient. AND ARMY RATIONS. By A. W. STOKES, F.I C. Sausages. While the "Food Control Regulations" lay down qualities and prices for sausages, requiring that the meat should be, for one price, 50 per cent and, for another price, 67 per cent by weight, it is necessary to be able to determine these limitations. Having analysed over 60 samples a description of the method I have used may be of interest. The main constituents of sausages are meat, brea, and water. A little salt and spice are usually added. Whilst the meat may be derived from any part of the animal it is, of course, in most cases impossible to determine either the animal or the part used. The water is the chief difficulty. In the following analyses of all meat products I have assumed that meat naturally contains 70 per cent and bread 40 per cent of water. The meat is dissolved by boiling in alcoholic soda solution, with formation of a soap from the fat. The insoluble matter is then placed in an aqueous caustic soda solution to dissolve the starch, which is then precipitated by strong alcohol. The actual method used is as follows:-The total solids, water, and ash are estimated in the usual way on 5 grms. of the material. Boric acid may be looked for in the ash. Ten grms. are boiled for one hour in alcoholic (methylated) solution of caustic soda (the alcohol being of at least 90 per cent, and the caustic soda of 5 per cent strength) under a reflux condenser. This treatment should dissolve the meat, form a soap with the fat, and leave the starch unaltered. This is filtered while hot through a small plug of slag-wool, and washed with strong hot alcohol. The filtrate is cooled and made up to 250 cc. with water, and 25 cc. evaporated to about 15 cc. (to remove the alcohol). The fatty acid is determined in this, using the Schmid method as in milk analysis. The filter plug and residue are returned to the original flask; about 100 cc. of cold aqueous 5 per cent soda solution are added and left for one hour, with occasional shaking This will dissolve the starch. The volume is made up to 500 cc. with cold water and filtered through a small slag-wool plug. Fifty cc. are collected, and about 100 cc. of strong alcohol (9 per cent) are added to precipitate the starch; after stirring and allowing to stand for half-an-hour the starch is filtered through counterpoised filter papers, washed with alcohol, dried, and weighed. The filtrations are sometimes difficult, but may easily be managed without a filter-pump if a filter flask be used to which is attached a short piece of rubber tube; mouth suction is applied to the end, the tube doubled over, and a clip applied to the part doubled. Calculation.-The fatty acids may be assumed to equal 95 per cent of actual fat. From the total solids are subtracted the starch and fat to get, by difference, the dry meat. To this "dry meat" is added 2:33 times its weight of water; this will give the fat-free flesh (called "flesh" in the following tables). To the starch is added o·66 times its weight of water to form bread. Frequently it will be found that the water actually present is above the quantities allowed by this calculation. This is due to the fact that in the manufacture of sausages the crusts and the bread used are soaked in water to soften them, and this water is only partially squeezed out before being chopped up with the meat. Very rarely the bread or the meat may contain less than the amounts I have Fat Bread Per cent. TABLE I.-Susages. No. 1. No. 2, No. 3. No. 4. Average of fo No. 5. samples. Flesh 668 48 660 584 536 66.3 572 0'5 The smallest amount of water found to be present was 48 per cent (No. 2); this sample it will be observed sums up to tog 1 per cent. This and three other samples were the only specimens showing that the meat and the bread contain less than the calculated allowances of water. No. 5, which contained the largest excess of water (237 per cent), was seen by microscopical examination to consist largely of tripe. In only a few cases were these samples examined microscopically; usually the indications were not particularly useful. Some few were analysed before and after cooking; generally the amounts of water and of fat could be assumed for these, the results are of little interest, diminished after cooking. But, as no standard for water and are not recorded here. and chicken, tongue and chicken, veal and ham, ham Meat Pastes. Meat pastes, variously described as ham and tongue, ham, tongue, and chicken, turkey and tongue, and wild duck, prepared by various makers, were analysed in the same way. The results of 14 of these show for the extreme percentages of each of the ingredients (Nos. I to 5), and the averages for all are given in Table II. The only sample out of these 14 that summed up to over 100 was No. 2, which, on the allowances for water in the flesh and bread, totalled to 104.9 per cent. This was in every respect far above all the other saniples, containing the least amount of bread and no excess of water. On reference to the maker I was informed that my results were within 2 per cent of the materials used. Of the samples the highest ash was 5.28 per cent, but this was mainly due to common salt; the lowest was 1.48, the average 2'9 per cent. No boric acid was present in any of these. To see how the process would work in various hands Messrs. G. A. Stokes and E. W. Wright kindly analysed a few samples of sausages for me. Their results were very similar to mine, as shown by the example Table III. specifying them to contain not more than 12 per cent fat, It seemed to him that the authors of the papers they had er 170 per cent water, or more than 2 grains of tin per heard read relied mainly upon the amount of nitrogen pound. They were not to have a greater acidity than the shown in the analysis, and reckoned this as representing equivalent of 72 cc. of N/10 soda in 100 parts. They con- the meat present. He would like to ask what would sisted of mixtures of meat, potato, baricot beans, peas, | happen if he sprinkled a little sulphate of ammonia over a carrots, and onions cooked in sealed tins. sausage or mixed some leather powder with it—would this be reckoned as "meat"? It was found easiest to pick out all the meat separately and to shred this finely. The vegetables could readily be mashed and mixed in the tin, the meat then added, and the whole well incorporated in the same tin so as to absorb any moisture therein. The analyses of these were performed as in the case of the sausages, omitting, however, any estimation of starch. For the acidity, 5 grms. were shaken with 100 cc. of cold water for one hour; an aliquot part was then titrated, after filtration, with N/10 soda. The results of 5 samples are appended (Table IV.). Per cent. TABLE IV. No. 4. No. 5. Average. 8.2 8.1 8.2 68.8 31.6 1'4 No. 1. No. 2. No. 3. 11'7 67'5 16:0 32:0 48.0 1.2 13 1'4 4'9 8.2 730 67'4 68.0 68.4 32'0 30'0 1.3 1 6 Fat Water Acidity Asb.. Only in one case (No. 2) was the amount of water slightly beyond the limit. In no case was any tin or boric acid detected. A review of the results of the analyses of the sausages and meat pastes shows that an excess of water, not natural to the meat and bread, may in the sausages reach about 24 per cent, and in the meat pastes 35 per cent. This high excess is usually due to the use of much bread; this soaked in water enables a large amount to be incorporated. In the United States the use of any starchy matter in sausages is forbidden. It is to be regretted that such is not the case in England. A sample like sausage No. 5, which contains about equal parts of fat (21 per cent), meat (26 per cent), bread (29 per cent), and excess water (24 per cent), would not be possible were it illegal to use bread. I am greatly indebted to Mr. G. W. Bender for his assistance in this work. DISCUSSION. The PRESIDENT, in opening the discussion, said that the Ministry of Food had consulted the Society in reference to the carrying out of their Sausage Orders under the following circumstances :-On January 21, 1918, the Department found it necessary to introduce the meatless days, and in that Order, known as the Public Meals Order, the expression "meat" was deemed to include sausages. In February the Meat Licensing Order was issued which forbade any person after March 15 from dealing in dead meat without a licence, and in this Order sausages were included as dead meat. This was revoked in Ireland on June 17, but later in the year the Ministry again issued an Order in which they then fixed the price of sausages according to their meat content, ignoring the fact that sausages were supposed by the previous regulations to be all meat. Pork sausages had also not been included in their Pig and Pig Products (Prohibition of Export) Order, as only bacon, ham, and lard were included in it. The Government Laboratory had tried to solve the mystery of what is now meant by a sausage of different grades, and the Society was glad to welcome their contribution to the discussion. Dr. VOELOKER suggested that it would be better if the Ministry of Food and other Government Departments, before making their Orders and putting out regulations as to how mixed foods should be compounded, would consult analysts generally and the Government Laboratory in particular as to whether it was possible to ascertain by analysis whether the composition could be ascertained, and not wait, as was here done in the instance of sausages, ., to hear the difcalties expressed at a subsequent meeting of this Society. He had heard no mention of microscopical analysis in this connection, and thought that it should be employed. The inclusion of soya bean meal, for instance, could be so detected. Mr. CRIBB inquired if the Food Controller had drawn up any definition of "meat," as the value of the methods proposed in the two papers under discussion must largely depend on what was meant by that word. In pre-war days he had had occasion to examine some sausages which consisted almost entirely of fat and bread, with a little connective tissue and only a trace of muscle fibre. Would such a mixture comply with the "Order”? An ingenious manufacturer might put a large propor tion of gristle and connective tissue into his sausage meat. This, owing to the low nitrogen factor for gelatin as compared with that for proteins, would seriously affect the figure for "flesh" obtained by the method recommended by Messrs. Stubbs and More. The presence of anything like a substantial proportion of liver, owing to the glycogen present, would give trouble in other directions. In view of these difficulties he would like to ses a number of analyses, by the methods now put forward, of sausages of known composition, as by this means only would it be possible to decide whether the problem set by the Ministry of Food could be satisfactorily solved. In any case he thought that the analytical figures obtained would have to be interpreted with great caution, and it would be quite unsafe to take action in cases anywhere near the border-line. With regard to sausage skins, to which the President had referred, some years ago he was consulted about a large consignment of sausages which on being sent to America were refused admission to that country, on the ground that they contained boric acid. The manufacturers bad put in none, and he was quite unable to find any in the sausages as a whole; but it transpired that the authorities in America had actually examined the skins separately, and had found an extremely minute trace of boric acid, which on examining a number of the skins he afterwards ascertained to be between one and two parts per million. The skins before use were kept in a saturated salt solution, and this was the only apparent source from which the boric acid could have been derived. Skins kept in this way would presumably be sterile.-The Analyst, xliv., No. 517, p. 127. PHYSICAL CHEMISTRY AND ITS BEARING ON THE CHEMICAL AND ALLIED Industries. By Prof. JAMES C. PHILIP, O.B.E., M.A., Ph.D., D.Sc. (Continued from p. 197). THE systematic study of homogeneous catalysis has led be illustrated by a couple of examples. The first of these to very definite and interesting results, some of which may refers to the influence of the concentration of the catalyst, and is based on a study of the rate at which diazoamingbenzene is converted into aminoazobenzene. This change takes place in aniline solution when an aniline salt, acting followed quantitatively, and the rate of change is expresas catalyst, is present. The course of the reaction can be sible by a velocity coefficient, the value of which varies in • Cantor Lecture (II.). Delivered before the Royal Society of Arts, Dember 8, for. From the Proceedings of the Moyal Society of Art Ixv., No. 5.51 CHEMICAL NEWS. May 2, 1918 Physical Chemistry and its bearing on Chemical Industries direct proportion to the concentration of the catalyst, other conditions being unaltered. This is apparent from the figures given in Table IV. 207 TABLE VI. t hours. Pressure in mm. 465.6 78.2 92 8 109 8 0'3 Experiments were made also in which the initial mixture contained hydrogen and oxygen in other than the volume ratio 2: I, and in which the partial pressures of the separate gases were ascertained at each stage, as well as the total pressure. A unimolecular constant we then calculated for the rate of disappearance of each gas separately, viz., kя, and ko, and it was found that the former alone was constant. This important result may be illustrated by the figures obtained with a mixture of 3 volumes of hydrogen with 1 volume of oxygen, circulated over porcelain at 430°. The quantities P, and Po, are the partial pressures of hydrogen and oxygen at the succes sive stages (Table VII.). Now it is found that the rate of inversion of cane-sugar at a given temperature in presence of acid of a definite normality varies notably with the nature of the acid. Thus the catalytic efficiency of hydrochloric acid in promoting the inversion of sugar is greater than that of sulphuric acid and acetic acid at the same temperature and the same concentration, and, indeed, for N/2 concentration, the velocity coefficients obtained in the three cases stand in the ratio 100:54:04. So far, then, as homogeneous catalysis is concerned, the evaluation of velocity coefficients provides a rational method of com. paring the activity of different catalysts under the same conditions. The majority of the technically important catalytic reactions belong, however, to the "heterogeneous" class, and in these cases the application of the reaction velocity formule already discussed and illustrated cannot be carried through to anything like the same extent. Indeed, the careful study of cases of heterogeneous catalysis on quantitative lines reveals the fact that other factors are operative besides mass action. This is brought out very clearly, for example, by Bone and Wheeler's research on the combination of hydrogen and oxygen at hot surfaces. In this work provision was made for the circulation of hydrogen and oxygen through a tube packed with frag. ments of unglazed porcelain and maintained at a constant temperature, the gradual combination of the gases which took place under these conditions being followed quanti tatively by determinations of the pressure from time to time. Plainly, as the reaction 2H2+O2=2H2O proceeds, the pressure falls regularly, and provides a record of the progress of the change. From such a record the velocity of combination of the gases may be calculated. On the ground that two distinct substances disappear during this reaction it might fairly be expected that the course of the change would conform to the bimolecular or the trimolecular type. The surprising result, however, has emerged that the rate of reaction is represented by the unimolecular formula. In support of this the figures in Table VI., obtained with normal electrolytic gas at 450°, may be quoted:-k is the velocity coefficient calculated by the unimolecular formula, k2 is that based on the bimolecular formula. From these and other figures it appears that the rate of change is proportional to the partial pressure of the hydrogen, and this must mean, as Bone has pointed out, that the formation of steam is an indirect process, dependent on a primary change, at the surface of the catalyst, in which hydrogen is concerned. The evidence favours the view that the catalytic action of porcelain depends on the occlusion of the reacting gases on its surface, and the results quoted above indicate that the rate of change is determined mainly by the rate of occlusion of the hydrogen. Hence in studying the catalysis of hydrogen and oxygen at hot surfaces it is not really the velocity of a chemical reaction that is being measured, but the rate of a purely physical process. The operation of the law of mass action is masked, and it may be that the chemical combination of the hydrogen and the oxygen at the surface of the catalyst is exceedingly rapid, perhaps instantaneous. The investigations to which reference has just been made laid the foundations for the introduction of what is known as "surface combustion,” in which the catalytic effect of hot surfaces in promoting combustion receives practical application. A homogeneous explosive mixture of inflammable gas and air is made to burn without flame in contact with a granular solid, the latter acting as an accelerator of the combustion, and becoming itself incandescent. In various ways, a description of which would lie outside the scope of these lectures, this surface combustion may be employed for such purposes as the concentration and evaporation of liquids, for heating muffle furnaces, and for steam raising. In another field, lying far apart from that of combustion, heterogeneous catalysis is found to present various features which are foreign to the law of mass action. Some of the most important catalytic reactions, including many of technical significance, are those which take place under the influence of enzymes. These are catalysts, formed by living organisms and of very complex nature, which promote in a remarkable degree many changes in organic matter. To this class of catalysts belong, for example, invertase, diastase, and the enzymes of yeast |