JDIT 10, 1914] 



SCIENCE 



75 



The Colorimetric Determination of Manganese by 

 Means of Periodate: H. H. Willard and L. H. 

 Greathouse. 



The solution of manganese salt containing excess 

 of nitric, sulfuric or phosphoric acid is boiled for 

 a minute after addition of potassium periodate. 

 The manganese is oxidized to permanganic acid, 

 the periodic acid being reduced to iodic acid. 

 Small amounts of hydrochloric acid are without 

 influence, being quickly oxidized to chlorine. The 

 concentration of acid above a certain minimum 

 may be varied within wide limits. In the presence 

 of iron, sulfuric or phosphoric acid must be pres- 

 ent to prevent the precipitation of ferric periodate. 

 By means of a colorimeter, the solution is com- 

 pared with a standard similarly prepared. 



Electromotive Behavior of Soluble Sulfides: R. C. 



Wells. 



From a study of the potentials shown by various 

 solutions of sulfides with a platinum electrode it 

 was concluded that the electromotive behavior of 

 the xwlysulfides depends on the relative propor- 

 tions of the sulfides present, but that in acid solu- 

 tions where free sulfur is apparently the only 

 oxidation product of sulfide ions the potential of 

 solutions which are very slightly oxidized can be 

 expressed by the equation 



JB = — 0.26 — 0.029 log[s--], 



since the concentration of the free sulfur is con- 

 stant and equal to its solubility in water. 



The Phase-rule Investigation of Addition Reac- 

 tions: James Kendall. 



The freezing-point modes of the two-component 

 system dimethylpyrone-acid have been examined for 

 a large number of organic acids and phenole. The 

 existence of thirty-seven addition compounds has 

 been demonstrated. The results obtained are dis- 

 cussed in their bearing on the constitution of 

 dimethylpyrone and the quadrivalence of oxygen. 

 The reaction is considered to be ionic, and the com- 

 pounds formed to be true oxonium salts. The 

 method is generally applicable to the study of or- 

 ganic addition reactions. 



Peculiar Action of Iodine: Chakles T. P. Fen- 

 nel. 

 Distribution of Caffeine and Antipyrin Between 

 Chloroform and Aqueous Solutions: "W. O. 

 Emebt and C. D. Weight. 

 Reaction in Non-aqueous Solvents : O. L. Babnebet. 

 Separation of Potassium from Sodium by Extrac- 

 tion of their Chlorplatinates with Acetone: O. L. 

 Babnebet. 



Some Compounds Belonging to the Ammonia Sys- 

 tem of Acids, Bases and Salts: E. C. Feanklin. 

 (1) The Action of Potassium Amide on the 

 Amides of Silver, Barium, Strontium, Calcium, 

 Lithium and Sodium. By Edward C. Franklin. 

 It will be recalled that the writer and his col- 

 laborators have prepared compounds of the for- 

 mulas, 



Sn(]SrK)j.4NH3, Zn(NHK),.2NH3, PbNK.2iNH3 

 and 



]Sr = Ti — NHK, . 



to which, in view of the analogy existing between 

 these compounds as derivatives of ammonia on 

 the one hand, and the stannate, zincate, plumbite 

 and titanate of potassium as derivatives of water 

 on the other, have been given the respective names, 

 potassium ammonostannate, potassium ammono- 

 zincate, potassium ammonoplumbite and potas- 

 sium ammonotitanate. Furthermore it will be re- 

 membered that similar ammono salts containing 

 thallium and magnesium have been prepared, an 

 accomplishment which is noteworthy in view of 

 the fact that the corresponding aquo salts are 

 unknown. It now appears that not only are the 

 above-mentioned salts formed in a manner similar 

 to that used in the preparation of potassium am- 

 monozinoate but that also the amides of silver, 

 barium, strontium, calcium and even lithium and 

 sodium enter into reaction with potassium amide 

 in solution in liquid ammonia to form sharply de- 

 fined products of the respective formulas, 



AgNHK.NHj, BaJSrB:.2NH3, SrNK.2NH3, 

 CaNK.2NH3, LiNK2.2NH3 and NaNK3.2NH3. 

 If the compound, Zn(NHK)j.2NH3, is properly 

 designated as potassium ammonozincate, and it 

 certainly is if the compound Zn(0Na)2 X HjO, is 

 called potassium (aquo) zincate, then these new 

 compounds must receive the respective names, 

 monopotassium ammonoargentate, monopotassium 

 ammonobarate, monopotassium ammonostrontiu- 

 mate or strontianate, monopotassium ammonocal- 

 oiumate or calcate, dipotassium ammonolithiumate 

 (or possibly lithianate) and dipotassium ammonoso- 

 diumate (or sodate or natronate). This procedure 

 is of course pushing analogy to the limit and it 

 may be that these products are not salts at all, but 

 are molecular compounds as represented by the 

 formulas 



AgNH^.KNH,, Ba(NH,)2.2KNH,, 

 NaNH„.2KNH2, 



etc., whatever the significance of such formulas 

 may be. The writer hopes, by transference meas- 



