4 
DR. A. E. H. TUTTON ON THE 
In type 2, the q {011} faces were larger, and the c {001} faces relatively smaller 
and often reduced to narrow strips. The r'{20l} faces were also somewhat more 
prominent, and more of the faces of o {111} and o'{ill} were developed. 
The c and p faces in many crops were affected by striation, but those crystals 
selected for measurement were wonderfully free from this defect, and several of the 
crystals measured were practically perfect, yielding brilliant single images of the 
signal throughout, offering no trace of ambiguity as to the position of the faces: 
The contact face (that parallel to the bottom of the crystallising vessel) was either 
c or p. 
The next table affords a comparison of the axial angles and axial ratios of the four 
salts containing nickel. The axial angle of the ammonium salt is almost identical 
with that of the caesium salt. The values of the axial ratios of the ammonium salt 
clearly indicate the existence of isomorphism between this salt and the three salts 
containing the alkali metals. 
Comparison of the Axial Angles and Axial Ratios. 
Axial angle. 
Axial ratios. 
Potassium nickel sulphate . . 
Rubidium ,, „ . . 
Ammonium ,, ,, . . 
Ceesium „ ,, . . 
A 
105° 0' 
106° 3' 
106° 57' 
107° 2' 
a : b : c 
0-7379 : 1 :O’5020 
0-7350 : 1 : 0-5022 
0-7373 : 1 :0‘5000 
0-7270 : 1 :0-4984 
The next table affords a comparison of the morphological angles of the four salts. 
Comparison of the Interfacial Angles. 
Angle. 
KNi sulphate. 
RbNi sulphate. 
CsNi sulphate. 
AmNi sulphate. 
f ac = (100):(001) 
o r 
75 0 
o / 
73 57 
o t 
72 58 
o / 
73 3 
as =(100):(101) 
45 48 
45 4 
44 21 
44 35 
sc = (101):(001) 
29 12 
28 53 
28 37 
28 28 
< 
cr' = (001) : (201) 
63 44 
64 36 
65 28 
65 5 
cs' = (001) : (101) 
38 33 
38 57 
39 22 
39 1 
sY = (101) : (201) 
25 11 
25 39 
26 6 
26 4 
[r'a = (201) : (100) 
41 16 
41 27 
41 34 
41 52 
[ap = (100): (110) 
35 29 
35 17 
34 48 
35 11 
pp = (110):(120) 
19 28 
19 28 
19 28 
19 28 
p'b = (120) : (010) 
35 3 
35 15 
35 44 
35 21 
[pb =(110):(010) 
54 31 
54 43 
55 12 
54 49 
< 
f cq =(001): (Oil) 
25 52 
25 44 
25 28 
25 34 
L qb =(011): (010) 
64 8 
64 16 
64 32 
64 26 
