22 Dr. E. J. Mills's Researches oji Melting-point. 



Table XIX. 





A v 



A, 



B v 



B 2 . 



B 3 . 





111-29 



111-50 



111-37 



111-53 



111-40 





•29 



•34 



•60 



•41 



•35 





•35 



•53 



•51 



•32 



•40 





•40 



•50 



•41 



•34 



•40 





•38 



•53 



•41 



•39 



•47 





•45 



•50 



•48 



•46 



•51 





•40 



•27 



•37 



•41 



•51 





•31 



•42 



•51 



•41 



•51 





•26 



•42 



•58 



■44 



•49 





•24 







•45 



•46 

 •51 

 •32 



•37 



•38 

 •31 





111-34 

 014 



111-45 

 •017 



111-46 

 •016 



111-41 

 •012 



111-43 

 014 



Probable error . . . 



Thermometer ... 



3 



2 



3 



3 



3 



3. « Dinitrophenol. — « dinitrophenol appears to have been 

 first observed by Armstrong, who, however, did not obtain it 

 in a state of purity ; the exacter definition of the substance is 

 due to Hiibner and Schneider (Zeit. Chem. xiv. p. 524). In 

 preparing it, I followed the method recommended by the last- 

 named chemists, depending more especially on the insolubility 

 of the baric derivative in boiling spirit of 90 per cent. When 

 the baric derivative was dissolved in water and treated with 

 aqueous hydric chloride, the hydric salt was precipitated : this 

 was afterwards dissolved and crystallized. 



a dinitrophenol has an extremely pale yellow colour when 

 crystallized from naphtha or spirit ; the powder has a deeper 

 shade; and the solution imparts a dark-orange tint to a tissue 

 on which it has been dried. 



A, B, C, D, E were distinct preparations. A and B had 

 been crystallized thrice from naphtha and thrice from spirit ; 

 C had been crystallized from water, aqueous potassic chloride, 

 and twice from spirit ; D had been made from a baric salt 

 twice extracted with spirit, after which it was crystallized 

 once from naphtha and four times from spirit*; E was formed 

 by uniting the remainders of A, B, and C, extracting the baric 

 salt thrice with alcohol, and crystallizing the resulting a dini- 

 trophenol once from naphtha and once from spirit. 



* The hot alcoholic solution was poured off from a red, quite insoluble 

 foreign >ub.?tance. 



