Gravimetric determination of manganese with 8-hydroxy-quinoline

Precipitates of manganese oxyquinolinate obtained from a mineral acid solution containing a slight excess of oxine by adding dilute ammonia, according to Berg’s second method, could be dried to constant weight at 150°C. and weighed. A slight superficial discoloration which may be observed in some cases is inappreciable even when dealing with small amounts of manganese. The composition of the dried precipitate corresponds to Mn(C9H6ON2 and contains 16·03% manganese. Satisfactory results are obtained in a single precipitation provided a large excess of oxine is not added. A large excess of oxine with or without the addition of strong ammonia tends to yield higher results. Double precipitation does not improve the accuracy of the results in such cases. The presence of large amounts of ammonium or sodium chloride does not appreciably affect the accuracy of the results. Small amounts of manganese ranging from 0·3 to 4·0 mg. could be satisfactorily determined in presence of large amounts of sodium chloride and strong ammonia

Determination of magnesium and residual manganese in rocks and minerals with 8-hydroxy-quinoline

The magnesia and residual manganese have been precipitated together with oxine, the content of the latter determined colorimetrically and that of the former calculated by difference in the analyses of samples of charnockite, leptynite and garnet. The results obtained are compared with those obtained in parallel determinations carried out by the pyrophosphate method and improved accuracy in the estimation of residual manganese as well as magnesia claimed

Colorimetric estimation of boric acid with pentamethylquercetin

A new method for the approximate colorimetric estimation of boric acid depending on the yellow colouration yielded by boric acid with pentamethyl-quercetin in presence of citric acid in anhydrous acetone medium has been described. The method is empirical in character and gives results with a maximum error of about 15% with quantities of boric acid ranging from 0·4 to 1·8 mg

Samarskite from Nellore District. Part II. Chemical composition

1. A typical sample of samarskite has been analysed and the results reported. 2. The thoria content of the sample is 1·98%. 3. The percentage of cerium earths present in this sample is relatively much smaller than found in samples from North America. Our sample contains 0·4% ceria. 4. Hexavalent uranium has not been found in the sample but this is of no special significance. 5. The radium contents is 1·0 gr. in 39·71 tons and the Nellore samarskite is nearly as rich as Katanga Carnotite in this element

A new fluorescence reaction for the detection of boric acid

A new fluorescence reaction for the detection of boric acid with resacetophenone and phosphoric acid has been described. None of the metallic radicles examined interferes while among the acid radicles chromate, bromate, chlorate, nitrite and fluoride do so to a limited extent. The reaction compares favourably with those described in the literature both as regards limit of identification and also interference. It has been shown that the test is applicable for the detection of micro-quantities of boric acid

The lanthanum nitrate test for acetate in inorganic qualitative analysis

The lanthanum nitrate test for the acetate ion has been examined for use in the routine analysis of mixtures of inorganic substances including the acetate, oxalate and tartrate radicles. A distillation method for the preparation of the test solution and a modification of this procedure in the presence of sulphites and thiosulphates are described. The results obtained are quite satisfactory and the test is recommended for general use

The constitutional features of anthoxanthins in relation to the morin reaction in analytical chemistry. Part I. Some naturally occurring hydroxy-flavonols and flavanones

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Fluorescence reactions with boric acid and o-hydroxy-carbonyl compounds, and their application in analytical chemistry. Part II. Detection of aromatic compounds containing C, H and O only

1. Addition of boric acid to aromatic compounds (C, H, and O only) of various types containing the, dissolved in concentrated sulphuric acid generally produces a marked intensification or a change in colour of the fluorescence exhibited by them in daylight or under the lamp In several cases the solution of the compound in sulphuric acid is itself non-fluorescent and fluorescence appears on adding boric acid. 2. In a few cases even when this group is present no fluorescence effects are obtained with boric acid. 3. 3 : 7-Dihydroxy-flavone and its 7-methyl ether are exceptions in that they give positive reactions with boric acid even though the above group is absent. 4. The fluorescence effects obtained with boric acid could be utilised for the detection of the in various types of aromatic compounds containing carbon, hydrogen and oxygen only. A positive reaction indicates the presence of this group but the converse is not true. 5. This reaction is more general than all the others described in literature and is also easily carried out

Colouring matter of the flowers of Hibiscus cannabinus: constitution of cannabiscetin

The colouring matter of the flower petals of Hibiscus cannabinus consists mostly of the glucoside cannabiscitrin along with small quantities of the corresponding aglucone cannabiscetin. The properties and reactions of these two substances are described along with those of some of their derivatives. Cannabiscetin forms a hexaacetate and a hexamethyl ether. It is a flavonol exhibiting similarities with gossypetin and herbacetin particularly in regard to alkali colour reactions and gossypetone reaction. It yields gallic acid on being subjected to alkali fission, its methyl ether producing trimethyl gallic acid. It is, therefore, concluded to be 3:5:8:3':4':5' hexahydroxy flavone

Pigments of cotton flowers. Part II. Uppam (Gossypium herbaceum)

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