ii6 Dr. WoLL ASTON on a Method 



circumstance excited some doubts regarding the correctness 

 of the estimate by which their diameter had been deduced. 

 Other wires were consequently drawn with the utmost care, 

 as to the quahty and substance of the platina employed, and 

 as to the proportional reduction of its diameter in the process 

 of wire-drawing. 



The extremity of a platina wire having been fused* into a 

 globule nearly J of an inch in diameter, was next hammered 

 out into a square rod, and then drawn again into a wire ~l'-^ 

 of an inch in diameter. One inch of this wire duly coated 

 with silver was drawn till its length was extended to 182 

 inches, consequently the proportional diminution of the dia- 

 meter of the platina will be expressed by the square root of 



182, so that its measure had become — = — ^. The 



253xi3'5 3425 



specific gravity of the coated wire was assumed to be 10,5, 

 and since the weight of 100 inches was 114 grains, its diame- 

 ter was inferred to be -^ of an inch, or just eighty times that 



of the platina contained in it. 



With portions of the platina wire thus obtained, and succes- 

 sively reduced in diameter, I had an opportunity of repeating 

 the trials of its tenacity with greater confidence in the justness 

 of the estimate, and the results shewed generally (though 

 with some accidental exceptions) that the process of wire- 

 drawing, which is well known to improve the strength of 



• I am indebted to my friend Dr. Marcet for the simple and easy method by 

 which the fusion was effected. A piece of wire, about six inches long, having been 

 bent to an angle in the middle, one half of its length was held in the flame of a spirit 

 lamp impelled by a current of oxygen, and its extremity was thus fused in about half 

 a minute. 



