Doxycycline Mg

posted on 24 Aug 2012 15:14 by doxycyclinemgeg
Doxycycline Mg

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200** C. It is described in the Pharmacopoeia as occurring in dry, white, very deliquescent masses. The fully hydrated salt, which contains six molecules of water, and compounds Doxycycline Mg with varying amounts of water down to the anhydrous form, are commercially obtainable. The appearance of the salt is comparatively little guide in judging of the amount of water it -contains, for a salt containing three molecules of water is very similar in appearance to one with two molecules. The simplest and most rapid means of estimating the amount of water in the salt is to titrate it by means of a normal solution of sodium carbonate at a temperature of about 100^ C, using phenolphthalein as an indicator. The end of the reaction is quite sharp. An inexperienced operator will be somewhat disconcerted by the appearance of pink color on the addition of phenolphthalein to the Digitized by Google 2'jS REPORT ON THE PROGRESS OF PHARMACY. solution of some samples, but this disappears on running in the solution of sodium carbonate. Chem. & Drugg., Mar. 21, 1908, 460. Barium Salts, Quantitative precipitation by Arsenic and Arsenous acids under certain provisions, which see under " Arsenic." Magnesium Carbonate Silica a Common Impurity, C. M. McClore gives the results of the chemical analysis of magnesium carbonate. Five of six samples contained small quantities of silica, to the presence of which he attributes the difficulty in filtering and keeping stock solution of magnesium citrate. Amer. Joum. Pharm., Aug., 1907, 365. EARTHS. Doxycycline Mg Aluminum Sulphides Preparation and Convenient Use for Preparing UfS, According to Fonzes-Diacon, aluminum sulphide is readily pre- pared by placing a mixture of aluminum and sulphiu: on a layer of cal- cined magnesia in the bottom of a mortar to prevent adhesion of the sulphide on heating the mortar and contents, yellow aluminum sulphide is quickly formed. This compound serves advantageously for preparing HjS, without the use of acids, a current of this gas being readily produced in the usual way by the simple addition of water. Pharm. Ztg.,lii (1907), No. 65, 681 ; from R^p. de Pharm., 1907, No. 7. Beryllium Proof of Divalenee, B. Glassman has found that when pure picric acid is dissoIVed in water, warmed, neutralized with beryllium car- bonate, filtered, and evaporated to crystallization, a yellow picrate crystal- lizes out. When dried in air and analyzed the Beryllium Picrate so obtained is found to have the formula [CeH,- (NOj)sO]jBe4-3H20. If this picrate is treated with ether and dried at 50 C, it gives up one molecule of water. The molecular weight of the anhydrous picrate was determined by the freezing-point method in aceto- phenone, care being taken that the latter was absolutely free from water. The molecular weight was found in two experiments to be 465 and 471.1^ while the calculated value is 465.1. Thus the divalence of beryllium is confirmed by this work. When the anhydrous picrate is treated with water it gives a basic picrate of the formula, [QH,' N02)aO],Be.2oBe(OH),. Chem. News, Aug. 16, 1907, 84; from Ber. d. D. Chem. Ges., 40 (1907), No. II. Beryllium Chromates Preparation and Composition, B. Glassmann obtains beryllium chromate, BeCrO^.H^O, by neutralizing a warm concen- trated solution of chromic acid with beryllium carbonate and crystallizing the salt by cooling. So obtained, it is in form of reddish monoclinic crys- tals. The salt is decomposed by water with separation of Basic Beryllium Chromate, BeCr04.6Be(OH) a yellow insoluble pow- der, having a constant composition, which may also be obtained by precip- itating a solution of beryllium sulphate with solution of ammonium chro- mate. Ber. d. D. Chem. Ges., 40 (1907), 2602. ^ t Digitized by VjOOQLC YTTRIUM EARTHS. 279 RARE EARTHS. Yttrium Group of Rare Earthy Study of Terbium and Dysprosium Compounds, G. Urbain and G. Jantsch have begun a study of the ele- mcDts of the yttrium group of rare earths in order to find out what relations exist between the different members of the series, and to devise less tedi- ous processes for Doxycycline Mg their separation than those hitherto employed. In their present paper they give the results of experiments with terbium and dysprosium, and describe the following compounds : Terbium peroxide, TbA; terbium nitrate, Tb( NO,) s.6H,0 Doxycycline Mg ; terbium sulphate, Tba( 804)8.- 8H,0; terbium chloride, TbCl8.6H20. Dysprosium does not form a peroxide. The salts of the oxide (DygOg) are light yellowish-green in color and have the following composition : Dysprosium nitrate, DyNOg.- SHjG; dysprosium sulphate, Dya(S04)8.8Ha0; dysprosium chloride, DyCl8.6H,0. Chem. News., Febr. 14, 1908, 75-76 ; from Compt. rend., 146 (1908), 127. Yttrium Earths Separation by Fractional Crystallization of Their Bromates. After pointing out *the deficiencies and objections to the dif- ferent methods that have been proposed for the separation of the rare earths from each other, either by fractional precipitation or crystallization, C. James observes that fractional precipitation to be Doxycycline Mg of value must be very rapid. Fractional crystallization is to be preferred, for it is much easier to carry out a large number of operations. As a rule, in fractional pre- cipitation methods, especially where dilute solutions are employed, a good deal, if not most of the Doxycycline Mg material, is washed away. It is highly desirable, therefore, that a method consisting of Doxycycline Mg fractional crystallization of some Doxycycline Mg type of isomorphous compounds, with greatly varying solubilities, should be found. With this object in view, the author has examined the sul- phites, Doxycycline Mg xanthates, succinates, double carbonates with sodium, glycollates, methylsulphates, normal propylsulphates, camphorates, iodates, sulpho- cyanides, sulphocyanide double compounds with mercuric cyanide, mono- chloracetates, roonobromsuccinates, oleates, ferrocyanides, bromates, etc., besides nearly every compound proposed in literature for the purpose of fractionation. The bromates are the best suited for the purpose of all those examined up to Doxycycline Mg the present time. The bromates are easily prepared by using barium bromate, which in turn is formed by mixing boiling solu- tions containing the required amounts of barium chloride and potassium bromate. As potassium bromate can be prepared cheaply the rare earth bromates are not costly to obtain. The rare- earth material, generally in the form of the oxalates, is mixed
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