Remarks on Professor Newcomb's "Rejoinder" 275 

 The following is a description of the fractures of the series: — 



No. 1 Bright white, highly crystalline. 



„ 2 Dull white, highly crystalline. 



„ 3 Gh* e 3 T 5 highly crystalline. 



„ 4 Grey, finely crystalline. 



„ 5 Dull fibrous, crystalline. 



„ 6 Bright purplish, highly crystalline, 



more than No. 1. 



„ 7. Very brittle. Bright purplish, large plates of crystal. 



„ 8 Bright purplish, smaller plates of 



crystal. 



,, 9 Bluish, very finely cryptoconchoidal. 



„ 10 Purple, fibrous. 



,, 11 Purplish grey, fibrous. 



„ 12 Bluish grey, conchoidal. 



„ 13 White vitreous, fine granular. 



„ 14 Yellowish white, fine granular. 



„ 15 White, extremely fine granular. 



„ 16 Grey, granular. 



„ 17 Reddish grey, granular. 



„ 18 Orange, coarse granular. 



„ 19 Light red, granular. 



The alloys from Nos. 12 to 16 are easily tarnished. 



From this it will be seen that antimony is very persistent 

 in its influence, and also that the colour of the " Regulus of 

 Venus " first appears in the alloy containing 75 per cent, of 

 antimony, and disappears in that containing 45 per cent. 



From these data it would appear that in the copper-antimony 

 series there are two alloys which may be assumed to possess 

 very definite compositions — viz. the " Regulus of Venus/' 

 SbCu 2 , and the alloy represented by the formula SbCu 4 . 



XXXII. Remarks on Professor Newcomb's "Rejoinder* 

 By James Croll, LL.D., F.R.S.* 



IN the c Philosophical Magazine' for last February Professor 

 Newcomb has done me the honour to reply to my remarks 

 in the October number on his Review of i Climate and Time/ 

 which appeared in the 'American Journal of Science ' for May 

 1876. With regard to this Rejoinder of his, I regret that I 

 must repeat what I said about his Review, viz. that nearly all 

 his objections are based on strange, and to me unaccountable, 

 misapprehensions of my reasoning and of the views which I 

 actually hold. I have no desire to continue this controversy, 

 * Communicated by the Author. 



