Ford and Bradley — Footeite and Connellite. 675 



formula. The mineral not only contains two or three differ- 

 ent acid radicals, but is unusually basic in character. It is 

 especially difficult to decide what part the small amount of 

 nitric oxide plays in the formula. The ratios derived from 

 Analyses II, III and IV are given below. 



II III IV 



CuO -911 or 18-6 -921 or 18-8 '922 or 18'8 



CI -. '208 4-2 -192 3-9 "198 4*0 



S0 3 -061 1-2 -039) -047 [ 



NO -006 r 



3.0 -931 19'0 -951 19-4 '933 19-0 



In deriving the above ratios the small amount of nitric 

 oxide was considered as isomorphous with the sulphuric oxide. 

 The only reasons justifying this view is that there does seem 

 to be a mutual variation in the percentages of the two radicals 

 and because of the small amount present it is obviously neces- 

 sary to consider the nitric oxide as playing some isomorphous 

 role in the formula. The effect upon the ratios, however, 

 would be slight, no matter how the nitric oxide was regarded. 

 The ratios derived from the three analyses point fairly clearly to 

 the following formula as expressing the composition of the 

 mineral, namely, 16Cu0.2CuCl 2 .lCu(S0 4 , (X0 3 ) 2 ).19H. 2 0. Or, 

 disregarding the nitric oxide, the formula might also be writ- 

 ten, 16Cu(OH) 2 .2CuCl 2 .lCuS0 4 .3H 2 0. 



Penfield's analysis agrees less perfectly with this formula 

 than do the newer analyses. In interpreting his analysis he 

 considered that a small amount of the water in the mineral 

 occurred as hydroxyl isomorphous with the chlorine and from 

 this viewpoint he derived the formula, Cu 15 (C1.0H) 4 SO ]6 .15H 2 0, 

 which written similar to the one given above would become 

 12Cu0.2Cu(C1.0H) 2 .lCuS0 4 .15H 2 0. While, at first glance, 

 this formula would seem to be considerably different from the 

 new one proposed above, it will be seen, by comparing Pen- 

 field's analysis with the theoretical composition as given in 

 column Yon p. 674, that the variation is not so very great. It 

 is to be remembered that Penfield had only 0*0740 g. of mate- 

 rial available for his analysis. Further, his assumption that a 

 part of the water existed as hydroxyl replacing some of the 

 chlorine was made in order to simplify his formula and could 

 not in the nature of the case be subjected to proof. In view 

 of these facts it is felt that the proposed new formula has 

 stronger evidence in its favor and better expresses the composi- 

 tion of the mineral than that assigned to it by Penfield. 



With the hope of obtaining more definite data as to the 

 chemical structure of connellite, repeated attempts were made 



