CHEMICAL NEWS,{ Jan. 19, 1917 Report on Cattle Feeding Experiments TABLE III.-Feeding Experiments with Cattle just over Six Months Old, 19 5-16. The Average Daily Rations per 500 lbs. Live Weight during Sixteen Weeks were 27 LOT III.-Wintered inside. 25 lbs. swedes, 6 lbs. seeds hay 1 lb. soya cake. 2 lbs. palm kernel cake. 4 2 II 4 2 I 27 O 2 19 O 2 11 8 ∞ 78 20 ино 213 21 I 12 3 13 9'5 I 5 10 ΤΟ I Sixteen Three-parts Bred Hoggs in each Lot. Daily Feeding Rations per 100 lbs. Live Weight. (a) (a) As the hoggs were not making satisfactory gains, lb. maize meal was added to each ration in the third month, with excellent results. Germany and about 3500 tons to this country. Up till the outbreak of war the industries dependent on these kernels were practically in German hands. Oil from palm kernels is used largely for the production of margarine, and is now invaluable for this purpose in this country. The Colonial Office Committee has recommended the imposition in the several West African Colonies of an export duty of not less than £2 a ton on all palm kernels exported from British West Africa, the duty to continue during the war and for five years afterwards, and to be remitted on all kernels shipped to, and crushed in, any part of the British Empire. This recommendation is now before the Legislative Councils of the various West African Colonies, and is likely to be put into operation shortly. The importance, therefore, of testing palm kernel cake as a feeding material for cattle and sheep is evident, especially when there is a deficiency of other foodstuffs. Palm kernel meal is found to be an excellent basis for a pig meal, and as more oil is obtained from palm kernels by means of the extraction process of which palm kernel meal is the by-product, it was also of the greatest importance to test extracted palm evidence whatever of interfering effects in the cadmium kernel meal as a feeding stuff. On the averages of the years 1912 and 1913, Germany imported the following:-248,000 tons of palm kernels; 109,000 copra (the dried fleshy part of cocoanuts); 445,000 tons linseed and linseed meal; 217,000 tons cotton-seed; 125,000 soya beans; and 84,000 tons peanuts (earthnuts). Considerable quantities of these (especially of palm kernels) are now diverted to this country, and it is of the greatest importance that the British farmer should become familiar with the by-products produced from them. Difficulty in some instance has been experienced with palm kernel cake not keeping well, but this difficulty did not arise last winter at Cockle Park. The cakes, kept in an ordinary granary, were in quite good condition after over six months. There is no doubt also that, although stock may not readily take to palm kernel cake at first, they will eat it quite well if it is not allowed to become stale in the feeding troughs, if it is not fed in too large quantities, and if it is judiciously fed and mixed with other foods. ON THE RATES OF SOLUTION OF METALS IN By R. G. VAN NAME and D. U. HILL. Discussion of Results obtained with Ferric Salts. TABLE VIII. contains a summary of the results given in the previous tables, each velocity constant being the averaged result of the various experiments performed under the conditions specified. These values have been obtained by one or the other of the two following methods(a) For groups of comparable experiments in which the results were normal they are the averages, for all members of the group, of the average reaction velocity in each single experiment. (b) For groups of experiments in which the constants showed an unmistakable trend neward or downward they are the averages of the initial velocities as found by linear extrapolation. Although where method (b) is used the constants so calculated must be given the preference as more truly representative, the values calculated by method (a) are placed beside them, enclosed in parentheses, for comparison. Considering first the upper section of the table, containing the ferric sulphate constants, we observe that in the presence of 5 molar sulphuric acid 5 metals give practically the same velocity, which, from the point of view of the diffusion theory, would be interpreted to mean that here the rate of diffusion of the ferric sulphate is determining the velocity. With decreasing acidity, however, the agreement becomes poorer, the metals tending to draw apart and to show individual velocities whose order is that of the electro-motive series, the more positive metal dissolving more rapidly. It is evident here that the specific nature of the metal has a distinct influence on the reaction velocity. Such results as these are seemingly in direct contradiction to Nernst's hypothesis of infinitely high reaction velocity at the boundary surface between two phases. Nernst's hypothesis, as we have already seen, demands that in all normal cases, that is, in all cases not affected by secondary disturbing influences, the observed reaction velocity shall be determined by the rate of diffusion of the active substance, and shall be practically independent of the nature of the solid, Now it cannot be denied that disturbing influences may have slightly affected some of the results in the table; in particular, the nickel constants are rather uncertain. On the other hand, there was no *From the American Journal of Science xlii., 301. experiments. Moreover, the distinctly systematic nature of the results in the table argues against the possibility that any considerable number of them represent "anomalous" cases. Finally, the decreasing constants obtained with silver were clearly traced to the retardation of the chemical reaction by the accumulation of silver sulphate, which would have only a trifling effect on the rate of diffusion. In short, these results furnish grounds for seriously doubting the general validity of Nernst's hypothesis. A study of the table seems to show that at one extreme we have velocities determined largely or wholly by diffusion, at the other velocities determined chiefly by the rate of the chemical reaction, and between them velocities in which we can readily detect the simultaneous effect of both influences. Although these results do not cover the full range from a purely chemical reaction velocity to a pure diffusion velocity it is evident that the transition from one to the other is gradual, not abrupt. This point becomes clearer on further analysis of the results. An increase in the concentration of free sulphuric acid above o 25 molar produces in all cases a marked decrease in the observed reaction velocity. In general, the activity of an oxidising agent is increased by a rise in the concentration of hydrogen ion. It will hardly be doubted that this rule applies in the cases with which we are dealing, and we should therefore expect that the free energy of the reaction with the metal would increase with increasing acidity. This is supported by the potentials in Table VI. so far as inferences can safely be drawn from the behaviour of electrodes which are imperfectly reversible. This table contains the single potentials of silver, copper, and cadmium against solutions of the same composition as those used in the reaction velocity measurements. we have already noted, the values show that with increasing concentration of sulphuric acid the metal in all cases becomes less positive or more negative toward the solution; that is, the change is in the direction of increasing free energy. As 3 27 (299) 171 (155) 395 (382) 392 3 80 (341) 3'75 (3:39) 3 96 (416) 374 (361) 3 30 (322) 1 67 (135) 1 63 (136) Ferric Chloride. 4'19 .. 4:14 Molar concentration of HCI. O'I. 3:44 (322) 0.5. 4:17 1.72 1 71 (163) 1 24 (III) 435 4 20 (4:30) effect of an increase in acidity upon the velocity of the For our purpose, however, the important question is the chemical part of the reaction with the metal. Although, in general, there is no necessary correspondence, even in sign, between variations in reaction velocity and variations in the magnitude of the change in free energy, there would seem to be here a rather strong probability that the chemical reaction in most or all of the cases with which we shall have to deal is accelerated rather than retarded by an increase in acidity. At all events we shall make this assumption as a working hypothesis, and shall adhere to it consistently throughout. We must assume, then, that sulphuric acid tends to CHEMICAL NEWS, Jan. 19, 1917 Report of Chemist, Department of Agriculture, USA accelerate the chemical reaction with the metal, but we find in Table VIII. that if the acid is present in more than 0.25 molar concentration it exerts a strong retarding influence on the rate of solution. From the standpoint of the diffusion theory the explanation of this effect is clear. The important factor here is the viscosity of the solution, which is increased in the ratio of about 2 5:1 when the sulphuric acid concentration rises from 0.25 molar to 5 molar. An increase in the viscosity retards the diffusion process by lowering the rate of diffusion, and, perhaps, to a slight extent, by increasing the thickness of the diffusion layer (see Van Name and Hill, Am. Journ. Sci., xxxvi., 552), and in this way depresses the rate of solution of the metal, this effect here outweighing any acceleration of the chemical part of the reaction resulting from the higher acidity. A predominance of the diffusion effect, however, does not necessarily exclude the influence of the chemical reaction, for we find that velocity constants in the same vertical column (that for 0.25 molar sulphuric acid, for instance), though they differ among themselves in a com paratively systematic manner according to the specific nature of the metal, thus showing the influence of the chemical reaction velocity, are all lowered by an increase in the viscosity. In other words, these result illustrate the case alluded to above, of a reaction velocity determined by the simultaneous influence and mutual relation of both factors, diffusion process and chemical reaction. Nor is there any reason for believing that such cases are unusual. On the contrary, it seems proper to regard the observed velocity as being normally the resultant of the simultaneous action of the two factors just mentioned. Cases in which one factor predominates to the virtual exclusion of the other are, therefore, merely limiting cases, though no doubt they occur very often in practice. This point of view appears to us to be the most reasonable and helpful one in dealing with heterogeneous reactions of the general type under consideration, and will be the one employed throughout the present paper in interpreting experimental results. The results obtained with ferric chloride, summarised in the lower section of Table VIII., tend to confirm, so far as their evidence goes, the conclusions drawn above from the experiments with ferric sulphate. These values are probably less accurate than those for sulphate solutions, and less stress can be laid upon small differences. They prove that cadmium and iron dissolve in ferric chloride at the same rate in the presence of o 1 molar hydrochloric acid, and probably also when the acid is o'5 molar. This indicates that in these cases the observed reaction velocities are essentially rates of diffusion. It is not clear whether the effect of this increase in acidity is to raise or to lower the observed velocity, but the change is at all events small, as would be expected in a case in which the viscosity change is almost negligible (about 3 per cent). (NOTE.-In a like manner, the fact that the ferric sul phate constants change so little between oor and o 25 molar sulphuric acid, may be ascribed largely to the smallness of the accompanying viscosity change). The same increase in acidity produces a marked rise in the rate of solution of copper. We would avoid laying any emphasis on the absolute values of these copper constants, on account of the complications already mentioned. Nevertheless, it may be pointed out that the relations of these two velocities to one another, and to the corre sponding values for cadmium and iron, involves nothing unexpected or inconsistent with the point of view stated above. The lower value for copper in o'r molar hydrochloric acid, as compared with cadmium and iron, seems to be due to the influence of the relatively slower rate, in the case of copper, of the chemical part of the reaction, this rate being accelerated by the increase in acidity to 05 molar, up to the point where the rate of diffusion predominates, thus tending to bring copper into agreement with the other two metals. To be continued). 9 REPORT OF THE CHEMIST, DEPARTMENT OF AGRICULTURE, Bureau of CHEMISTRY, WASHINGTON, D.C., U.S.A. October 14, 1916 SIR,-I submit herewith the report of the work of the There was marked advancement during the year in the work of the Bureau of Chemistry, both in the development of agricultural chemistry and the administration of the Federal food and drugs act. More than fifty scientific investigations were completed. The results have either been published or are in the process of publication. Among them may be mentioned the discovery of a new sugar, studies on the moulds and bacteria found normally in foods or producing spoilage in them, investigations upon torage and ptomaine poisoning, upon the physiological action of coal tar dyes, upon vitamines, пpon saponins, and upon the proteins of peanut, of kafir, and other seeds. A large number of cases involving violations of the food and drugs act have been sent to prosecution. The number of civil and criminal actions recommended, however, is not a complete index of the success attained in securing protection for the consumer under this law. Manufacturers of food and drugs, mcre and more, are showing a willingness to comply with the regulations, and in many cases have improved their products so as to anticipate expected requirements. To such manufacturers the service and regulatory announcements have been of direct assistance. In these announcements manufacturers and others concerned with the operations of the food and drugs act obtain ample notice of the department's opinions with regard to various trade practices and through this, as well as through other channels, are notified promptly of all changes. These announcements are supplemented by publication of the results of investigations which have developed improved methods of producing foods and drugs. The producers and manufacturers of food products also have been assisted directly through practical demonstrations of better methods of preparing and conserving foodstuffs. The development of methods for preventing avoidable waste and spoilage of food products and the devising of new and valuable by-products have had special attention with the object of relieving as far as possible the prices paid by the consumer for finished products by the elimination of losses and waste. Special emphasis has been given by those in charge of the regulatory work in the past year to the control of drug products and in safeguarding the public from food subject to spoilage or pollution. Such foods if contaminated or improperly handled are liable to produce infection or poisoning and thus constitute a serious menace to health. With the object, therefore, of making the food and drugs act a hygienic measure as well as a preventer of economic fraud, the bureau has given especial attention to the interstate traffic in unclean milk, spoiled eggs, polluted oysters, and spoiled canned goods. The interruption of imports has made it particularly important to the health of the people to curb the traffic in spurious synthetic drugs, because exceptionally high prices have offered unusual temptation to the sophisticator. Rigid enforcement of the Sherley amendment aimed at the false and fraudulent labelling of medicines was continued as a measure necessary for health protection. As is pointed out in the report, much of the success in enforcing the food and drugs act has been due to the effective co operation developed between State food, drug, and dairy officials and the Federal regulatory force. Research. Plant Chemistry.---Investigation of the nitrogenous compounds of kafir, Andropogon sorghum, has shown that fully one-half of them are soluble in hot 70 per cent alcohol. The soluble nitrogen consists in great part of a new alcohol-soluble protein, the percentage composition of which has been determined. It contains the amino acids lysin and tryptophan, both indispensable to the nutrition of animals. These are not found in zein, the corresponding protein of maize. Now that this is known a rational attempt can be made to learn how kafir may be fed to make it no less valuable than maize. The peanut, Arachis hypogaea, and two globulins which have been separated from it have been found to contain an abundance of di-amino nitrogen. This form of nitrogen is indispensable to the nutrition of animals and is contained in inadequate amounts in the common cereals from which most feeds are derived. Peanut press cake should, therefore, prove to be an easily accessible material to make such cereal foods more efficient. In co-operation with the Bureau of Animal Industry it is planned to make a practical test of this matter. From the jack bean, Canavalia ensiformis, two globulins and an albumen have been separated and studied. The nitrogen distribution in cotton and tomato seed, cowpeas, corn, corn germ, and wheat has been determined. Many analyses of forage plants of the arid and semiarid West were made for the Bureau of Plant Industry. New saponins have been isolated from Yucca angustifolia, Yucca radiosa, Yucca filamentosa, and Agave lecheguilla. A comparison of the surface-tension effect of a series of saponins with their hæmolytic power failed to disclose any inter-relation of the two properties of the saponins. The glucoside in the leaves of upland cotton has been found to be quercimeritrin. The results of this work are in preparation for publication. The volatile oil distilled from the flowers has proven attractive to the boll weevil. The results of the study of cyanogenesis in the common grass, Tridens flavus, showing that during maceration cyanogen may disappear, have been published. This observation signifies that many of the physiological studies upon cyanogenesis need revision. The study upon boron absorption by plants discussed in the report for the year 1915 has been published. A phytochemical laboratory has been established. It will undertake chemical investigations of the proximate principles of those plants which are of especial importance in connection with the enforcement of the foods and drugs act. ment of Sugar and Acid in Grapes During Ripening,” has been issued. Flora of Foodstuffs.-An investigation of the range of conditions under which organisms of the Bacillus botulinus group may cause sickness or death in human beings and in domestic animals has been started. It was found that a strain of this organism obtained from a food poisoning case produced a very powerful poison. In cooperation with the Bureau of Animal Industry this poison was shown to affect rabbits, donkeys, and horses very quickly, cats in some cases and not in others, and not to affect fowls. Because the losses to individual packers of sardines from swelled cans may be as high as 30 per cent of the yearly pack, this form of spoilage has been studied in the hope that means for preventing this waste may be found. The organism causing spoilage very rapidly forms spores which are killed only at high temperatures. Therefore, aside from ordinary cleanliness, careful processing at high temperatures is necessary to prevent the subsequent swelling of cans. In the "red feed" within the stomachs of "belly-blown" sardines a gas-producing bacterium, pathogenic to guinea pigs, has been found. A sporebearing, gas producing anærobe identical with that found in sardines was isolated from two different consignmerts of spoiled sweetened condensed milk. B. mesentericus ruber was found to be the cause of the rose-pink colour of certain spoiled sweetened condensed milks. A general comparative study of the mould flora of the food-stuffs subjected to inspection has been begun, carefully distinguishing accidental organisms present resting spores and those active in producing changes in the substrata. as The study of the effect of storage on bottled waters has shown that B. coli, B. typhosus, and B. dysenteria inoculated into bottled mineral waters do not multiply, except the first two, which, in some instances, increased slightly during the first two days of storage. This was followed by a decrease in numbers. In a water fractically free from dissolved solids, B. coli persisted in greatly reduced numbers for more than six months. A yellow micrococcus, multiplying rapidly, was found to be due to air contamination. The manner in which commercially bottled water changes its flora in one to six months was studied in considerable detail. Bulletin No. 369, "Bacteria in Commercial Bottled Waters," was issued. The results of a comparison of bile with lactose buillon for determining the presence of B. coli in water were also published. The United States Public Health Service has been assisted by the Bureau of Chemistry in making sanitary surveys of oyster beds. The results of a study of the preparation for and the transportation to the market of oysters, of a comparative study of bacteriological methods for the examination of oysters, and of a comparative bacteriological examination of oyster-shell liquor and oyster meats have been prepared for publication. Carbohydrates.-A new sugar, the only heptose hitherto discovered in nature, d-manno-ketoheptose, has been separated from the avocado. The data are ready for publication. A large number of investigations upon the preparation, the mutarotation, and the rotatory power of sugars and sugar derivatives have been completed and prepared for publication. Some of the results were pub-panying differences in structure. lished during the year in the following papers :-"The Acetyl Derivatives of the Sugars"; "The Isomeric Pentacetates of Glucosamine and Chondrosamine"; "The Isomeric Tetracetates of Xylose and Observations Regarding the Acetates of Melibiose, Trehalose, and Sucrose"; "A Fourth Crystalline Pentacetate of Xylose and Some Related Compounds"; "A Second Crystalline d-Fructose Pentacetate"; "Crystalline 3-Methyl Fructo side and its Tetracetates"; "The Preparation of Melibiose"; "Bromoacetyl Xylose and B-Triacetyl-methylxyloside." In co-operation with the Bureau of Animal Industry a manuscript has been prepared showing that one member of the group of moulds known as Aspergillus niger produces ten times as much oxalic acid as others, without accom Papers have been published upon the occurrence of sucrose in relatively large amounts in a new seedling grape and upon the occurrence of sucrose in grapes of American origin. Bulletin No. 335, entitled "Develop It has been found that the common moulds Penicillium camemberti and Aspergillus niger produce substances reacting with ferric chloride like phenols, a matter of significance in detecting mouldiness in foods. It has also been found that the so-called salicylic acid reaction of the Japanese distilled liquor, sake, is in reality due to an acid formed by the mould used to ferment the rice from which sake is distilled. Mould products of this type may be mistaken for preservatives such as salicylic acid. An as yet undetermined species of ergot was discovered in caraway seed. Anti-neuritic Substances.-A variety of synthetic compounds have been made and tested physiologically. Several have been found to possess anti-neuritic properties similar to natural "vitamines." In collaboration with the CHEMICAL NEWS,} Jan. 19, 1917 Report of Chemist, Department of Agriculture, U S.A. 31 United States Public Health Service a crystalline anti-volatile esters in citrous oils and extract, of alcohol in the neuritic product was isolated from yeast and some evidence presence of phenol, of phenacetine and salol in admixture, obtained regarding its identity. A study of the nutritive of tartaric acid, and of raffinose by enzymatic hydrolysis, and medicinal value of cod-liver oil and extracts thereof have been published. was begun. One paper has been published and three nearly completed. Cereals, Flour.-Studies have been made upon the grading of flour and upon the determination of grades of four with especial reference to the bleaching of flour. It has been found that the particles of various sizes in flour differ in chemical composition and in baking qualities. The work on flour substitutes has been continued, and a report on the determination of moisture in bread has been made. Chemical studies have been made upon the changes that take place in the deterioration of oats and in the bleaching of inferior oats. Studies upon rice milling by-products have been completed. Bulletin No. 330, "The Milling of Rice and its Mechanical and Chemical Effect on the Grain," has been issued jointly with the Bureau of Plant Industry. Spices.-Studies have been made of pepper, mustard, celery, caraway, and poppy seed, savory and sage leaves, and saffron to determine their constants as a guide in regulatory work. The determination of oxalic acid in pepper and cinnamon has led to a revision of the statements in the literature on this subject. Gingerol, the pungent principal of ginger, an oily liquid boiling at 227229° C. at 6 mm. pressure, and paradol, isolated from grains of paradise, have been studied. Fats and Oils.-In co-operation with the Bureau of Plant Industry a bulletin has been issued upon peanut oil. A piper has been issued upon American charlock oil. Drugs and Pharmacology.-Papers have been published on "The Stability of Nitrous Ether" and on the "Periodides of Paenacetin, Methacetin, and Triphenine." The results of investigations upon the "Periodides of Antipyrin, Iodantipyrin, Pyramidon" have been completed for publication. Studies upon the heavy metals that may contaminate foods have been continued, and some of the results pub lished under the title "The Influence of Heavy Metals on the Intestines." Papers upon the action of citrate and is decomposition in the body and upon the elimination of malate have been prepared for publication. An article on the toxicity of a series of oil soluble dyes in which it is shown that some of them are eliminated in the urine combined with glycuronic acid has been finished and will soon be published. As a by-product of the study of the toxicity of water-soluble dyes containing iodine in the molecule, a research upon the influence of iodine and sodium iodide on the circulation has been printed. It has been found that digitalis and adrenalin antagonise the toxic heart action of oil of chenopodium while caffein is synergistic. The result of this investigation has been published. Insecticides and Fungicides.-A tree-banding material has been developed which has been used by the Bureau of Entomology in its gipsy moth campaign. It promises to prove superior to, and cheaper than, the materials now in use in this country. The Federal Horticultural Board has been further assisted in the fumigation of cotton bales, and the process has been so improved that a large part of the hydrocyanic acid used is recovered. One of the largest plants is now operating by this method. In co-operation with the Bureau of Plant Industry attempts are being made to so modify the formula for Bordeaux mixture as to render it more efficient, while at the same time reducing the amount of copper therein. The results of investigations upon the identification and determination of lactic acid in biological producte, upon the separation of lithium from the other alkali metals, upon a study of the Kjeldahl method for determining nitrogen, upon the freezing-point of milk as a means of detecting water, upon the detection of watered milk by means of simplified molecular concentration constants, upon the detection of ergot and moulds in food and drug products, upon the determination of the quality of gelatin by the measurement of its mutarotation, and upon the quality of commercial litmus papers have been prepared for publication. A method has been devised for distinguishing between bottle fermented and artificially car. bonated wines. The collation of the mass of information upon methods of food and drug analysis accumulated by the Bureau described in the report for 1915 has made great progress. Forty-five subjects were finished during the year, making 66 in all since the work was begun. Much of the work is more than compilation, since the aim is to present the Bureau's collective experience during the past fifteen years. This requires not merely the critical sifting of the Bureau's records, together with a study of the literature, but also not infrequently independent research. Conservation of Foodstuffs. Poultry, Eggs.-A precocling plant has been developed, cooled by ice, capable of chilling 15.000 lbs. of eggs and poultry a week, costing, installed, approximately 800 dols. With ice at 3 dols. per ton it has been found in actual commercial use to effect a saving of at least 22 dols. per carload in handling and chilling. The project upon improving the methods of fleshing poultry for the market has been continued. The work upon the transportation of perisnabies has been facilitated by the improvement of the method of installing resistance thermometers in refrigerator cars so that the temperature of the interior of a considerable number of cars may be observed simultaneously. The results of the previous work on damage to eggs in transit are being seen plainly throughout the country in greatly lessened waste at destination. Reports for the metropolitan district of New York City indicate that 41,161 dozens arrived broken during the calendar year 1915, while approximately twice that number were broken on arrival during 1914. In the study of the cold storage of eggs particular attention has been paid to the devising of methods to prevent stored eggs from acquiring the socalled "storage taste. Bulletin No. 224, "A Study of the Preparation of Frozen and Dried Eggs in the Producing Section," has been issued. An investigation has been made of the contents of the crop of fowls for the purpose of furnishing data to detect the feeding, as a makeweight, of excessive quantities of sand just before slaughtering. Fish.-Demonstrations in the preparation of fresh shrimp for the market with cleanliness, suitable boiling in brine, and thorough cooling has been of material value to the shrimp shippers of the southern east coast in the conduct of their business. Studies of fish transportation to prevent decay have been continued. Perhaps no other perishable food is shipped long distances with so little knowledge of what is required to insure arrival in good order. The work was begun in Florida, and at the end of the shipping season transferred to the Pacific coast, where transcontinental hauls are under observation. A Yearbook article upon the fish industry was published. Many analyses of food fish have been made which show that the data now on record are inaccurate because, as a rule, they were made without consideration of the season when the fish were taken. The in press. studies upon the chemical changes taking place in fish in Analytical Methods.-Methods for the estimation of freezer storage begun last year has been continued. A paper upon the reduction of Asv. to AsIII. by cuprous chloride and the determination of arsenic by distillation as arsenic trichloride has been published, while others upon "The Preparation and Properties of Lead Chlor-arsenate -Artificial Mimetite" and "The Arsenates of Lead are |