410 RECORD OF SCIENCE FOR 1886. 



can be readily obtained by the action of aqueous hydrofluoric acid on 

 diazoamido compounds. He describes fluorbenzeue (CeHsFl) boiling 

 at 84° to S5'=>, pLvrafluortolueue boiling at 110° to 117°, fluornitroben- 

 zene, fluoraniliu, and other bodies. It appears that the replacement of 

 hydrogen by fluorine changes very little the boiling points of the bodies, 

 but greatly increases their specific gravities. (Ann. Chera., ccxxxv, 255.) 



On Platoso- Oxalic Acid, by H. G. Soderbaum. — Doebereiuer formerly 

 obtained, by the action of oxalic acid upon the sodium salt of platinum 

 dioxide, a salt of a copper-red color, which he regarded as platinous 

 oxalate. Souchay and Lensseu assign it the formula PtNa2C408+4H20. 

 This salt has much analogy with the platinum sulphites, since the solu- 

 tion gives neither the reactions of platinum nor those of oxalic acid. 

 We may therefore regard this compound as the sodium salt of platoso- 

 oxalic acid, which has been isolated. 



The salts of platoso oxalic acid are very remarkable, because they 

 occur in isomeric or rather polymeric forms. 



For the preparation of the sodium salt sodium chloro-platinate is 

 heated with an equal weight of sodium hydrate. The residue is treated 

 with water, which dissolves out sodium chloride, leaving a yellow pow- 

 der, NajO, 3PtO2,0H2O. More of it is obtained by the addition of hydro- 

 chloric acid to the solution of sodium chloride, avoiding excess. It is 

 washed with cold water and washed with one and a half parts of crys- 

 talline oxalic acid. Carbonic acid escapes, and there is obtained a solu- 

 tion of an intense blue color, from which cold slender brown needles of 

 a metallic luster are deposited. This salt is collected upon a filter and 

 repeatedly washed with boiling water. There filters first a yellow solu- 

 tion, then a greenish or blue one, and lastly a solution of a reddish- 

 brown. From the last liquid the mass of the sodium salt is deposited 

 on cooling, crystallized in capillary needles of a coppery luster. The 

 first solution after some time deposits lemon-yellow prisms of an isomeric 

 salt. The intermediate solutions deposit mixtures of the two salts. 

 Both salts yield with silver nitrate a yellowish-white precipitate of 

 microscopic crystals of the silver salt of platoso-oxalic acjd. On decom- 

 posing this silver salt with the calculated proportion of hydrochloric 

 acid we obtain an indigo-blue solution, containing platoso-oxalic acid. 

 We may obtain the salts of the acid either by the double decomposition 

 of the sodium salts or by neutralizing the free acid with bases or car- 

 bonates. With the brown sodium salt there are obtained salts of a 

 brown, greenish, or blue color; but with the yellow salt we obtain iso 

 meric yellow or orange salts. The free acid generally gives salts of the 

 former class, i e., of a dark color, but by repeated crystallizations yellow 

 salts may be obtained. Several metals belonging to the zinc group form 

 dark-colored salts most readily ; others, for instance silver, yield yellow 

 salts, and others again form with equal ease either dark or yellow salts. 

 The tri- and tetra-atomic metals give both dark and yellow salts, but of 



