NEWS according to the amount of resin in the fatty acids. Taking the mean combining weight of resin as 347, then the percentage is easily calculated; it is reported both on 100 of dry fatty matter and on 100 of soap. Twitchell's test experiments are eminently satisfactory, and I have now pleasure in confirming them by my own tests: 1. Sample of distilled fatty acids containing no resin, when treated as described, showed o'7 per cent resin. 2. The above distilled fatty acids, to which were added common resin to the extent of 22'5 per cent, showed, when treated as above described, 23°3 per cent of resin, which, after deducting the o°7 per cent found in No. 1, gives exactly 22.5 per cent, or the amount which was added. 3. Soap made from palm oil and other fats, but no resin, gave 0.8 per cent resin. 4. Another soap made from fatty matter of unknown origin, but no resin, gave 1'0 per cent resin. This, it should be observed, was of a dark colour, and evidently contained some altered or oxidised oily matter. 5. Soap which showed by Gladding's test 6 per cent of resin, gave 4'9 per cent by Twitchell's process. united filtrates are diluted to 1 litre, and 500 c.c. placed in a clear white beaker and tinted with methyl orange; N/10 alkali is then dropped in till the liquid acquires the usual colour, after which a little phenolphthalein is added, and the addition of standard alkali continued till a permanent pink is established. The number of c.c. used in the latter titration are due to the soluble acids, and are calculated to caprylic acid. The fatty acids in the flask, and any little on the filter, are dried and weighed, and then dissolved in alcohol, and titrated with N/2 alcoholic alkali. The alkali so used, together with that required for neutralisation of the soluble acids, and deducted from the total alkali, gives the alkali existing in other forms than as soap. Of course, if desired, the soap may be decomposed with standard H2SO4, and the alkali required to neutralise the methyl orange noted, which, deducted from the total acid used, would give the acid equivalent to the alkali existing in all forms. In this manner we get Total alkali The following examples illustrate the method: The above results are all that may be desired, and I have now to show how the process may be still further shortened without any sacrifice of accuracy. This can be done by leaving out the washing and dissolving in No. 1-Soap from Cocoanut Oil and other Fats (Highly alcohol direct. A few drops of methyl orange are then Watered). Total Alkali by Titration, 2.06 per added and alkali til neutral to this indicator; phenolCent Na2O. phthalein is then added, and the titration completed as before. The alkali required in the first case is for the Weight of soap taken neutralisation of the free hydrochloric acid, and is of Weight of insoluble fat acids course neglected. That required to neutralise to phenol-C.c. of N/2 alkali to neutralise phthalein is of course due to the resin, and is calculated as such. THE writer, who was the first to point out the error attendant on the use of the alcohol method of determining free caustic alkali in soap (CHEMICAL NEWS, vol. lix., p. 280; Four. Soc. Chem. Industry, vol. viii., p. 479), advised, when both free fat and free caustic alkali are present simultaneously, the adoption of the following method: Determine, firstly, the total alkali in the usual manner. Then determine the amount of alkali required to neutralise the isolated fatty and resin acids from a weighed quantity of the soap. Obviously the difference is the alkali present as hydrate, carbonate, or silicate of soda, &c. In the same paper above mentioned the following sentence occurs:-"Supposing palm, nut, or cocoanut oil to have been used in the fabrication of the soap, the determination of the Na2O required to neutralise the fatty acids becomes inaccurate, owing to the solubility of the lower fatty acids; hence another complication arises. The error, of course, may be of greater or less extent, according to the nature of the fatty matter of the soap.' Fortunately, this error can be completely excluded by operating in a very simple manner as follows: 1. The alkali, in all forms, is determined by titration with standard acid in the usual manner. 2. Another weighed quantity of the soap is decomposed in an Erlenmeyer flask with a slight excess of dilute H2SO4, and the flask kept on the water bath till the fatty acids separate quite clear. The flask is then placed in ice water to cool, and then filtered. The fatty acids are washed three times successively with 250 c.c. of boiling water and allowed to cool each time and filtered. The C.c. of N/10 alkali to neutralise ...... 17'145 grms. 16.1 13.35% = 8:05 normal. 4'2 = 0'42 normal C.c. of N/10 alkali to neutralise soluble acids 4'2=0°42 17'145 H =1'53 per cent combined alkali. Total alkali (Na2O) Total fatty acids Per cent. 2.06 1'53 0'53 = 0'36 caprylic. 13:35 13771 SEPARATION AND DETERMINATION OF TELLURIUM. By E. DONATH. After In the determination of tellurium by the older method In precipitating tellurium by glucose in a boiling alkaline solution, as proposed by Stolba and used by Lad. Kästner, the separation is complete and soon effected. The deposit of tellurium can be either weighed on a tared filter or dissolved off the filter by dropping upon it nitric acid, moderately diluted and heated (2 parts nitric acid and I part water, with a few drops of sulphuric acid). The solution is then concentrated in a small porcelain capsule, and the residue, after gentle ignition, is weighed as tellurous acid, TeO2. soluble tellurates, the formation of which must be avoided. The dry mass obtained is ground finely in the capsule with an agate pestle, and moistened with con. centrated soda-lye, which becomes strongly heated by the transformation of the nitrates. After digestion for thirty minutes, a little more soda-lye and a corresponding quantity of water are added, the liquid is filtered off, and the tellurium is precipitated in the filtrate by boiling for at most twenty minutes with a pure solution of glucose, and it is either determined as such or as tellurous acid.Zeit. Anal. Chemie. DETECTION OF ADULTERATIONS OF BASIC By DR. MORGAN. In the Agricultural Section of the German Congress of Naturalists and Physicians the author pointed out various methods for the qualitative detection of adulterations in basic slag. The loss on ignition is important. If the sample is genuine there is no loss. If it amounts to I per cent, the sample is almost always adulterated. The The author's proposed method-precipitation by standetermination of the specific gravity also gives a clue, nous chloride or an alkaline solution of stannous oxide-especially in the case of sophistication with redonda led to no satisfactory results. The separation in an acid phosphate. The author does not use for this determina. solution by means of hydrosulphurous acid was quite tion a solution of mercuric potassium iodide, but bromo successful. A solution of this acid can be easily and form (specific gravity = 2'9). rapidly prepared by digesting zinc clippings with aqueous sulphurous acid, or by covering the clippings with a concentrated solution of sodium bisulphite and cautiously acidulating the solution with a little hydrochloric acid. The deep yellow solution thus obtained, which must be filtered before using, precipitates tellurium at once in the cold, and, if not too dilute, in the form of flocks which subside readily. If the hydrosulphurous acid is not decomposed, the tellurium is separated as such; if the liquid is heated, and even otherwise, in consequence of the almost inevitable decomposition of the hydrosulphurous acid, the tellurium subsides mixed with tellurium sulphide, and the liquid becomes opalescent in consequence of finely suspended sulphur. In concentrated hydrochloric solutions and with a suitable excess of hydrosulphurous acid the precipitation is complete after heating for fifteen minutes. The washed precipitate is rinsed through the perforated filter into a tared capsule, a little concentrated acid is added, the solution is evaporated down, and the residue, after slight ignition, is weighed as tellurous acid. This rapid process has the disadvantage that it is impracticable in presence of many metallic oxides. Thus, salts of bismuth are precipitated by hydrosulphurous acid at common temperatures, and on heating the liquid other metals of the H2S group are precipitated by the hyposulphurous acid formed on the decomposition of the hydrosulphurous acid. On using a pure solution of an alkaline tellurite, concordant and accurate results were obtained by precipita. tion with glucose in an alkaline solution, and with hydrosulphurous acid in an acid solution. The opening up of products, or minerals containing tellurium, and its separation from accompanying elements, were attempted by the author in various manners. After many fruitless experiments, he succeeded in developing a method which meets all fair demands as regards accuracy and despatch. About 3-4 grms. of the very finely pulverised sample are gradually oxidised in a porcelain capsule with a minimum of concentrated nitric acid, and the thick pasty mass is heated until all excess of nitric acid is eliminated. The temperature must not be raised high enough to decompose the less stable iron, copper, and bismuth nitrites. In this case, there would be formed from the tellurous acid, telluric acid; and, subsequently, very sparingly Treatment with dilute soda-lye separates redonda phosphate and basic slag. If there is an impurity of redonda phosphate a very copious precipitate is produced. particles are found if redonda phosphate is present, but If the coarsely ground sample is examined yellow not in case of a pure basic slag. that of Jantsch and Schucht. The best method for a quantitative determination is The P2O5 of basic slag is perfectly soluble in 5 per cent citric acid, but not that of redonda phosphate. "Taffin" slag behaves like basic slag, but it remains suspended in bromoform. Dr. Loges, of Posen, mentioned a new spurious material said to be of English origin. The small sample which he had obtained contained 4 per cent caustic lime, 6'4 per cent calcium carbonate, as well as calcium fluoride. It is probably sophisticated with Welsh phosphate.-Chemiker Zeitung. DETECTION OF FORMLESS FERMENTS BOTH the physiological and the chemico-legal demonstration of unstable poisons in blood encounter difficulties depending mainly on the fact that the colouring-matter of the blood (if the red globules are dissolved by putre. faction, morbid processes, or improper treatment such as the addition of water), forms a tarry mass which it is difficult to treat chemically and which is perfectly useless for physiological experiments. The removal of this tarry colouring-matter is generally effected by plentiful dilution and boiling with acetic acid, or precipitation with alcohol, with potassium ferrocyanide and acetic acid, or with uranium nitrate. In all these cases the serum albumen present in the blood along with the blood-pigment as well as all albumenoid enzymes and toxalbumens are simultaneously precipitated, and thus the detection and the isolation of the enzymes and toxalbumens is rendered impossible. But if we had an agent which would throw down the colouring-matter of the blood, leaving all other substances in solution, and chemically unaltered, we should have made NEWS an important step towards the isolation and detection of the enzymes and toxalbumens. Zinc-powder may be regarded as such a precipitant for hæmoglobine. In forensic chemistry which is generally concerned with stale, offensive blood, this agent has the advantage that it renders the specimen almost inodorous even if several weeks old. The completeness of the precipitation is not interfered with by the age of the blood. The following conditions are essential for successful precipitation: the zinc and the albumenoids, is filtered, the filtrate is neutralised and injected into a second animal. If this animal, in contradistinction to the former, exhibits no phenomena of poisoning, the symptoms observed in the former subject must have been occasioned by an albumenoid poison, as in such dilute liquids other poisons are not precipitated by potassium ferrocyanide, or at most a portion of strychnine, which can be easily detected in the precipitate. The isolation of the poisonous albumenoid substance 1. In quite recent blood, freshly drawn from normal can be undertaken only in the main portion of the original men or other animals, which is always alkaline, the alka-filtrate, either by treatment with alcohol in the ordinary linity must be neutralised before the addition of the zinc manner or by "salting out" with ammonium sulphate. powder. The same holds good of the blood of dead In those toxalbumens, however, which do not admit of bodies a week old in which ammonia has been formed. the above mentioned methods of precipitation, e.g., those On exposure to the air, or remaining in the body, the of venomous spiders, a more complete isolation of the normal alkalinity of the blood is lost within 1 to 2 days. poison is not yet practicable. Diseases-especially fevers-often reduce the alkalinity before death to such a degree that the zinc may be added directly. 2. The blood must be free from methæmoglobine. If this substance is present the blood is allowed to remain in an open vessel without dilution or shaking until the last trace of methæmoglobine has disappeared. It is known that this disappearance often ensues within 24 hours, whether in the corpse or in jars, even when the original quantity of methæmoglobine was very considerable. 3. The blood must be diluted with at least 3 to 5 volumes of water. 4. The zinc-powder must be as pure as possible, containing nothing but zinc and zinc oxide. 5. The quantity of the zinc-powder must be equal to a quarter or a half of the original weight of the blood. 6. The mixture must be energetically shaken for a considerable time. If these conditions are observed a complete separation of the colouring-matter of the blood is almost always effected, so that even on washing the precipitate with much water in the filter-press or in the filter-pump nothing returns into solution. The yellowish brown colouring-matter thrown down, but remains in the filtrate. Distinaly recognisable quantities of zinc are to be found in the filtrate only if compounds of organic acids were present in the blood. Otherwise mere traces of zinc exist as zinc albuminate, in smaller proportions the more the zinc powder is free from zinc oxide. As the deposit-a solid, contained in the serum of some kinds of blood is not reddish-brown, bulky mass,-retains no organic poisons except traces of hydrocyanic acid and carbon monoxide, we have in the filtrate all the glycosides, alkaloids, ptomaines, toxalbumens, enzymes, amides, &c.; in short, the examination of the filtrate is exclusively important for forensic chemistry. Concerning the solid residue we need merely remark that the hydrocyanic acid may be removed from it by extraction with alcohol and carbon monoxide by exhaustion in the air-pump. The filtrate is incomparably more suitable than the original blood as well for the chemical as for the physiological detection of poisons. If its action upon animals is to be examined it is only requisite to shake up a portion with a drop of solution of sodium sulphide, and to filter off the precipitate of zinc sulphide. If the proportions are duly adjusted the liquid, free from zinc and sodium sulphide, can be injected subcutaneously into a mouse or into the circulatory system of a kitten. However, the filtrate can often be applied without the elimination of the zinc. The bacteria which swarm in putrid blood are almost entirely left behind in the residue. Where an absolute determination of bacteria is required the filtrate may be again passed through a Chamberland filter and thus the last residues of the germs may be removed. If the animal experimented upon exhibits grave phenomena of poisoning, a second portion of the original filtrate is mixed with a drop of solution of potassium ferrocyanide and a little acetic acid, the precipitate, which includes all If the second experimental animal does not remain in health, but is taken ill like the first, we have a proof that the poison in question does not belong to the albumens, -at least not to those precipitable by ordinary means. The entire filtrate is then freed from albumen and the limpid filtrate is examined for other poisons by Dragendorff's method.-Chemiker Zeitung. NEW METHOD FOR THE EXAMINATION OF FERROCYANIDES, FOR DETERMINING THE VALUE OF PRUSSIATE MELT, AND FOR ESTIMATING THE FERROCYANIDE IN SPENT LAMING'S MASS. By R. ZALOZIECKI. THE method is founded on the fact that the ferrocyanides in a solution of potassium or sodium ferrocyanide may be completely precipitated in the form of double ferrocyanides of zinc and alkali by an addition of zinc carbonate and the introduction of a current of carbonic acid gas. The equivalent quantity of potassium or sodium separated by the zinc from the ferrocyanides is transformed into the corresponding potassium or sodium carbonate, and the quantity of the ferrocyanide originally present may be found by an alkalimetric determination of the alkaline carbonate formed. According to the experiments of the author, 3 mols. potassium ferrocyanide yield on decomposition 2 mols. zinc ferrocyanide, whilst I mol. potassium ferrocyanide remains undecomposed. The double salt therefore corresponds to the formula 2Zn2FeCy6+K4Cy6, and the decomposition is represented by the following equation3K4FeCу6+4ZnCO3=2Zn2FeCy6+ K4FeCу6+4K2CO3. The reaction always takes place uniformly in heat, and even in the cold the transformation of potassium ferrocyanide is effected according to the above equation. A solution of sodium ferrocyanide behaves differently, since in the cold there is formed a double salt poorer in zinc, though in heat the same decomposition takes place as with potassium ferrocyanide. It is therefore always necessary to operate in heat. The zinc carbonate to be used in the process is obtaine by precipitating in heat a solution of zinc sulphate with sodium carbonate; the basic carbonate thus obtained settles rapidly, and may be easily washed. It is convenient to weigh approximately whilst in the moist state the basic zinc carbonate obtained from a known quantity of zinc sulphate, and preserve it in a closed glass jar. The author generally uses in his experiments 20 grms. moist zinc carbonate, corresponding to 225 grms. zinc. Such an excess does not affect the results, but the decomposition may be produced completely by a much smaller quantity of zinc. In a determination of ferrocyanide the solution of the | salt is mixed in a small flask with a known quantity of zinc carbonate, and carbonic acid is passed into the heated solution for from half to one hour. The treatment with carbonic acid is continued until the original decided yellow colour of the solution has disappeared, or until the addition of a ferric salt to a portion of the clear liquid no longer gives a blue precipitate. When cold it is put into a measuring flask containing 250 c.c., filled up to the mark, and filtered through a dry filter into a dry flask, wherein 50 c.c. of the filtrate are titrated with sulphuric acid of known strength as indicator. According to the above equation the quantity of the ferrocyanide can be calculated from the potassium or sodium carbonate thus determined, as four equivalents of potassium or sodium carbonate represent three equivalents of ferrocyanide. The author observed that the presence of large quantities of alkaline sulphates or chlorides lead to the formation of a compound richer in zinc. This effect is annulled if at the same time there is present an excess of alkaline carbonate. In examining the salts of prussiate melts the presence of sulphates must be taken into consideration, and in case the sulphates are present in considerable quantity a known excess of potassium or sodium carbonate must be added prior to the introduction of the zinc carbonate; otherwise the results will be too high. For the examination of prussiate melts the author gives the following directions:-10 grms. of melt are dissolved in 100 c.c. of water, the volume of the insoluble residue being taken into consideration. In 25 c.c. of the solution the alkalinity is determined with normal acid and methyl orange: 50 c.c. of the solution are treated, as described above, with 10 grms. moist zinc carbonate, carbonic acid is introduced for half an hour into the hot solution, which when cold is placed in a 100 c.c. flask, and filled up to the mark; 50 c.c. of this solution are titrated with decinormal acid after the number of c.c. acid required for the alkalinity of the mark have been added. If, in the determination of the alkalinity in the coloured solution of the melt, the change of colour is difficult to recognise, the solution can be exactly neutralised with dilute sulphuric acid, and, prior to the decomposition with zinc carbonate, 20 c.c. of a normal solution of potassium carbonate. There is no difficulty in titrating back, as the liquid is colourless after the decomposition. If the acid is so standardised that I c.c. corresponds to o'00 grm. potassium carbonate, the c.c. of the acid consumed in neutralising the potassium carbonate formed, multiplied by 08, give the per cents of anhydrous potassium ferrocyanide, and if multiplied by o'92 the percentage of hydrous ferrocyanide in the original melt. Sulphocyanides, if present, do not affect the result. Potassium sulphide is indeed converted into zinc sulphide and potassium carbonate, but this decomposition has no effect, as the potassium sulphide present is included in the result on determining the total alkalinity with methyl orange as indicator. The method is applicable also in determining the ferrocyanide in spent "mass" from the gas purifiers (Laming's mass). Zaloziecki proceeds as follows:-20 grms. of the mass, in a state of fine division, are gently heated on the water-bath for fifteen minutes with 20 c.c. 10 per cent potassa lye and a little water in a 100 c.c. flask. When the entire quantity of the ferrocyanide present is thus dissolved it is let cool, and the flask is filled up to the mark: 50 c.c. of the clear solution (or, more correctly. 45 c.c. if measured with a burette, as 20 grms. of the mass take up a volume of 10 c.c.), corresponding to 10 grms. of the sample, are boiled in a 100 c.c. flask over an open fire until the ammonia is entirely expelled, and it is then accurately neutralised with dilute acid. To facilitate the neutralisation a few drops of solution of phenolphthalein may be added, and the acid dropped in from a burette until the red colour disappears. On neutralisation NEWS the sulphur separates out and the liquid becomes turbid, but this does not interfere with the further determination. The expulsion of the ammonia may also be effected by the addition of milk of lime, and the lime may next be removed by the solution of potassa, which renders the liquid clear. The solution thus prepared, in which all the ferrocyanogen is combined with potsssium, cannot be at once submitted to treatment with zinc carbonate and carbonic acid, as potassium sulphate (or chloride) is present in quantity, and would interfere with the reaction. He therefore first adds to the solution 20 c.c. of normal potassium carbonate, and then undertakes the decomposition in the manner described above, adding 5 grms. moist zinc oxide, and then passing carbonic acid for half an hour through the hot solution. When the reaction is completed, and the liquid is cooled, the flask is filled up to the mark, and one-half of the liquid-representing 5 grms. of the mass is titrated with decinormal acid and methyl orange. The quantity of normal acid equivalent to the normal potassium carbonate added (10 c.c.) is either added at the outset or deducted from the total sum of c.c. of acid consumed. If the acid has been so standardised that I c.c. represents o'001 grm. potassium carbonate, the c.c. of acid consumed in titrating back, if multiplied by the coefficient 0'46, will give the percentage of crystalline ferrocyanide existing in the purifying mass.-Zeitschrift Analyt. Chem., vol. xxx., 484. PROPERTIES OF PRECIPITATES, &c. By E. WALLER, Ph.D. ONE division of Fresenius's book on Analysis" treats of "forms," in which are given the "Quantitative properties of the various forms in which substances are separated for the purpose of weighing and determination. If has seemed to the writer that those properties might be described in a manner more convenient for reference, and also that there might be added the properties of various precipitates, &c., which are used in analytical work for purposes of separation. Of course only those properties are considered which have a bearing on the usual manipulation of the different substances. For convenience the information has been grouped under the heads |