THE MINERAL CONSTITUENTS OF THE TUBERCLE BACILLI. BY E. A. DE SCHWEINITZ AND MARION DORSET. August, 1895,' the writers published the results of some analyses showing the composition of the tubercle bacilli when grown upon different media. Depending upon the character of the media used, the amount of ash varied from two to four per cent. It seemed desirable to make a careful analysis of the ash in order to see which of the mineral constituents of the animal body would be most largely utilized by the germ and consequently necessary for its satisfactory development. The bacilli used for this work had been grown upon neutral beef broth containing one per cent. of peptone, one-half per cent. salt, and seven per cent. glycerol. The cultures, after heating in order to kill the germs, were filtered and washed well with boiling water. The washed bacilli were then dried over sulphuric acid, finely powdered, and thoroughly extracted with pure ether and ninety-eight per cent. alcohol. After the last extraction the bacilli were again dried and ignited at a low red heat until practically all the carbon had been burned. The ash, which was almost pure white in color, was dried to a constant weight at 100° C. The total ash available for analysis was 1.453 Examination showed that sulphates, chlorides, and carbonates were not present in the ash. The method used for the determination of the constituents of the ash were those prescribed for the analyses of the ash of plants. The results calculated upon the dry ash were as follows: The high percentage of phosphorus pentoxide and the absence of other acid radicals in this ash are very noticeable. While it is probable that some of the chlorides and sulphates 1 This Journal, 17, 605. may have been washed out of the germ in the process of preparing it for analysis, no chlorides were present in the germs after washing; the fact that the amount of phosphoric acid. obtained in the ash is slightly lower than the total amount of phosphoric acid obtained from the whole germ, would indicate that chlorides and sulphates are practically of no importance in the composition of the germ, while their presence in the culture media in minute quantity appears to be necessary for the satisfactory development of the germ. Chlorides and sulphates if dissolved out would have been present probably as cell contents rather than as part of the germ. Ash analyses of comparatively few germs have been made, and the only ones which give data that may be reported here are the analyses made by Cramer,' who found that the composition of the ash of the cholera germs varied greatly, depending upon the quantity of sodium chloride and sodium phosphate that were used in the preparation of the media. In normal media the results were as follows: If the amount of sodium chloride in the media was increased, the percentage of chlorine in the ash was more than doubled, while the percentage of SO, found was reduced to one per cent., and the percentage of P,O, was largely diminished, being reduced to 9.64 per cent. When sodium phosphate was added to the media the percentage of chlorine was found to be 9.99 per cent., the percentage of P,O, 34.30 per cent., SO, 2.24 per cent., of potassium 4.97 per cent., of sodium 31.83 per cent., of calcium 1.29 per cent., of magnesium 0.12 per cent. These results differ greatly from those found in the examination of the ash of the tubercle bacilli. As noted above, the media used for the growth of these latter germs was a normal material containing one-half per cent. of salt, but without the addition of any 1 Archiv. für Hygiene, 28, No. 1. phosphates or other salts. Consequently the high percentage of phosphorus pentoxide can be attributed only to the fact that phosphorus as well as the calcium and magnesium are absolutely necessary for the development of the tubercle bacilli, and were derived by it from these elements as normally present in the media. In arrested cases of tuberculosis in animals, we often find hard, gritty, calcareous nodules. These nodules in healed tuberculosis contain tubercle bacilli. In other cases of healed tuberculosis where calcareous nodules are not present no bacilli as a rule are found. It is easy to trace a very close connection between these nodules in healed tuberculosis, and the composition of the ash of the germ. The high percentage of fat contained in the body of the tubercle bacilli, which we have noticed in previous papers, in conjunction with this high percentage of calcium and magnesium phosphate in the ash, give grounds for some interesting speculation. Phosphates and cod-liver oil are two materials always strongly recommended in cases of tuberculosis. As the germs of this disease seem to demand a large quantity of food containing phosphorus and also rich in fat, it is but a fair supposition that in giving the drugs above mentioned, we are supplying to the animal body those constituents which are very important for its proper nourishment, the supply of which is constantly being levied upon by the germs of the disease. The question might be asked whether in this method of treatment we are not really feeding the bacilli rather than the individual. But just as an exhausted soil can be made valuable by the addition of constituents which are deficient, so we may assume that the administration of specific materials containing the elements that the germ has utilized, should act in a similar way in increasing the vitality in the animal body. These of course are speculations, based, however, on certain known data. We trust that a still further study which is in progress, including the albuminoid constituents of the tubercle bacilli, may throw some light upon their development and chemical action in the animal body. BIOCHEMIC LABORATORY, WASHINGTON, D. C. THE SPECIFIC GRAVITY OF SODIUM CHLORIDE TH SOLUTIONS. BY H. C. HAHN. Received April 8, 1898. HE specific gravity and expansion by heat of salt solutions have not received the attention of chemists and physicists to the extent which they deserve. The data for common salt, for example, are only sufficient for technical purposes. To the best known determinations of the specific gravity of sodium chloride solutions belong those of J. A. Bischof, G. Karsten, and G. T. Gerlach. Since the publication by Bischof in 1810, so many improvements in physical apparatus and more exact determinations of certain necessary factors, have been made, that we need not take his determinations into consideration. Those of G. Karsten, in 1846, show extraordinary diligence. His method is to weigh a glass ball in a salt solution, which stands in a large vessel full of water to be heated gradually. In this method there is danger of the one beam of the balance getting warmer than the other by the ascending current of heated air from the lamp and the hot water. Nevertheless, his method is the best, if modified as explained below. Further, Karsten did not determine the coefficient of expansion of his glass ball, but used the one determined by Munke, which is not admissible in very exact determinations. He does not state that the degrees of the mercurial thermometer were corrected to those of the air thermometer; nor that in calculating the weight of the weights and the glass ball in the vacuum, he took into consideration the amount of water and carbon dioxide in the air. The determinations by Gerlach' are the best; but some of the same and some other objections have to be raised against them. He did not determine the coefficient of expansion of his pycnometer, but used the one of Dulong and Petit. Reducing the weights to the vacuum, he assumed the atmosphere to have been saturated with water, which very probably was not the case. He compared the different specific gravities with that of water of 15°, instead of with that of 4°. He did not correct the degrees of the mercurial thermometer, and 1 Spec. Gewichte der gebräuchlichsten Salzlösungen von verschiedenen Concentrationsgraden, Freiberg, 1859. instead of calculating a formula for each series of determinations, he calculated the specific gravities of the solutions of certain percentages by interpolation from the two nearest determinations. Some of these defects may yet be corrected. This I have done and give in the following the details with different methods to eliminate errors. For the numbers in column 1 different formulas may be calculated, according to the number of figures used. To the values for five, ten, twenty, and twenty-five per cent. corresponds the formula: s=0.999,03 +0.007, 203 +0.000,009,4 +0.000,000,4 p3, when s signifies the specific gravity and p the per cent. of sodium chloride. But the values for naught and fifteen per cent., as calculated by this formula, would be: 0.999,03 and 1.110,54, which are slightly erroneous. A formula calculated according to the method of least squares, with the use of the 4th power is: S=0.999, 12+ 0.007,072,54 +0.000,024,206,76p*, which gives the values of column 3. The sum of least squares is 0.000,000, 175. The differences of the observed and calculated values are larger than of those obtained by the foregoing formula. I calculated |