THE TECHNOLOGIST. [June 1, 1885. 



488 ON MAGNESIUM. 



and the pith for sago, independent of many other uses, are objects of 

 very great importance. 



" From observations made in the Botanic Gardens at Calcutta, well- 

 grown, thriving trees produce about six leaves annually, and each leaf 

 yields from eight to sixteen ounces of the clean fibre. In the same 

 garden there are now (1810) many thousand plants and young trees, 

 some of them of above twenty years' growth, with trunks as thick as a 

 stout man's body, and from twenty to thirty feet high, exclusive of 

 foliage. They are in blossom all the year ; one of them was lately cut 

 down, and yielded about 150 lbs. of good sago-meal." 



ON MAGNESIUM. 



The existence of magnesium was revealed by Sir Humphry Davy. By 

 means of large electric batteries at the Royal Institution, Albemarle 

 Street, London, he succeeded in decomposing sundry earths and alkalies, 

 and demonstrated their metallic bases. Thereby he opened a new con- 

 tinent to scientific exploration—a continent as yet virgin in many 

 regions, as America or Australia. 



Magnesium dates from Davy, in 1808, but for half a century it stood 

 for little but a name in the catalogue of elements. In combination 

 with oxygen, as the medicine magnesia, it was familiar to everybody, 

 but as a metal it has been a very great rarity, preserved in bottles and 

 sold in grains at fancy prices, and even then but selduni pure. Indeed, 

 in several manuals of chemistry it is so incorrectly described, that it is 

 evident the authors have never seen the metal in simplicity. 



It would appear that Davy did little more than indicate the exist- 

 ence of magnesium. His discoveries were too numerous for him to 

 track out each in detail, and twenty years elapsed ere any one was 

 tempted to resume the study of magnesium from the point where he 

 left it. In 1827, "Woehler, having obtained aluminium by the decom- 

 position of the chloride of aluminium by potassium, it occurred to 

 Alexander Bussy, the Parisian chemist, that it would be possible to 

 divorce magnesium from its combination with chlorine in the same 

 way. He tried and succeeded. He fused some globules of potassium 

 in a glass tube with anhydrous chloride of magnesium, and to his 

 delight obtained globules of the metal. In 1830 he made the process 

 the subject of a memoir addressed to the Royal Academy of Sciences * 



* "Journal de Chiraie Medioale," March, 1830, and " Annales deChimieet de 

 Physique,'' vol. xlvi., page 434. 



