454 S. H. BARRACLOUGH. 
also to be light—e.g., nautical, physical and astronomical instru- 
ments. The working of magnesium requires heat. At 450°C. it 
~ ean be rolled, pressed, worked, and brought into complicated forms. 
Screws and threads can be made from magnesium and these are 
considerably sharper and more exact than those from aluminium. 
Owing to its cheapness, magnesium can also be ae in the manu- 
facture of a variety of useful articles.” 
The present tests were made principally on rolled or drawn 
rods, nearly half an inch in diameter, together with a few con- 
*firmatory tests on specimens of the magnesian wire used for 
illumination purposes before the now more usual “ribbon” was 
introduced. 
Tensile tests of six of the rods, made just as they were received 
from the manufacturer, gave the following results :— 
Bs No. | hic gi | Elastic s 
Bek ome! Boab Eat ee] 
| 1 483-3500 | -23,800 | 8,800} 42 2,040,000 
2 433° «3250 | 22,050 ies 3 1,860,000 
| 3 | -442 | 3200 | 20,900 10,780| 1:8 | 2,060,000 
; 4 435 | 2900 | 19,500} 8,400| 2:5 | 1,830,000 
| 5 ‘424 | 3500 | 24,800| 7,090] 3-1 1,930,000 
6 “432 | 3300 | 22,500 5 2:3 
The extensions were measured by means of a Thurston extenso- 
meter, over a length of four inches. Two further tensile tests 
were made on specimens turned in the lathe to the dimensions 
stated, and with the following results. The metal can be turned 
with great ease. 
| Diam Breaking {| Elonga- | Contraction 
ba ne pared Load ths. | tion per | of Area per 
per sq.in.| cent. cent. 
1 | “336 | 2502 | 28,399 | 2-67 | 74 
2 | ‘351 | 2275 | 23,500! 3:00 1-76 
In these tests an attempt was made to obtain an autographic 
stress-strain diagram, but the apparatus ordinarily used for that 
purpose proved unsuitable for such a material as magnesium. 
Roe SI eg RES eee cee See ee ee 
tee crt Sire el ae ER rgb yin Bea ee ae ee ee OP 
aS whee Bay a 
