OF ZINC AND ANTIMONY. 353 



radiated crystalline texture, and a trace of this structure could be still discovered even in 

 the alloy containing only 4 per cent of antimony. It might be supposed that, on 

 returning to the alloy of 42.8 per cent of zinc, and increasing the amount of antimony, 

 we should obtain crystals containing an excess of antimony ; but so far is this from 

 being true, that the slightest excess of antimony entirely changes the character of the 

 crystallization. On crystallizing an alloy containing 41.8 per cent of zinc, not a trace 

 of any prismatic crystals could be seen, but in their place there was found a confused 

 mass of thin metallic scales, which, as will soon be shown, are imperfect crystals of 

 SbZng. Thus it appears that, although perfectly formed crystals of SbZug can be ob- 

 tained containing 55 per cent of zinc, they cannot be made to take up the slightest 

 excess of antimony. A more remarkable example of break in continuity than the 

 lower limit of SbZng I have never seen. It was brought to notice very forcibly on at- 

 tempting to recrystallize a quantity of alloy of 42.8 per cent of zinc, which had already 

 afforded large and definite crystals of SbZiig, after adding a very small piece of anti- 

 mony, when no trace of crystallization could be obtained except the scales described 

 above. 



In order to obtain crystals having the composition of SbZuj, that is, containing 33.5 

 per cent of zinc, it is necessary to crystallize an alloy at least as low as 31.5 per cent 

 of zinc. At this point large compound crystals are obtained corresponding to the large 

 crystals of SbZuj. On increasing the amount of zinc in the alloy up to 33 per cent, 

 the proportion of zinc in the crystals appeared to increase in the same ratio, so that the 

 curve of SbZn^ is, at this part, a straight line parallel to the curve of SbZug. It 

 should, however, be noticed, that the extent of this line. A- /, is so limited, that a very 

 small error in the analyses might change very considerably its direction. The cr)'stals 

 of SbZn,>, containing an excess of zinc, are smaller and more frequently isolated than 

 those containing exactly two equivalents. A similar fact, it will be remembered, is 

 true of the crystals of SbZug. At the alloy of 33 per cent of zinc the definite crystals 

 of SbZua begin to disappear, and are succeeded by thin metallic scales, which, as the 

 two following facts will prove, are imperfect crystals of the same crystalline form. 

 First, the scales from the alloy of 33 per cent are frequently found having a definite 

 crystal as a nucleus, when it is evident that their surflxces are extensions of the basal 

 plane O of Fig. 3. Secondly, the scales twin together like the large tabular crystals of 

 SbZuj, forming a cellular structure ; and the angle between two scales thus united 

 measured, with an application goniometer, approximatively 115° 30', and was therefore 

 equal to the basal angle of the definite crystals. These scales continue up to the alloy 

 of 41.8 per cent of zinc, becoming, however, constantly less abundant and less distinct. 



VOL. V. NEW SERIES. 48 



