CHEMICAL SCIENCE. 229 



zinc necessary is about | of the weight of the gold to be extracted, that is, 

 an equivalent of zinc to one of gold, With less the whole of the gold is not 

 obtained. If more than an equivalent be employed, the mercury retains a 

 considerable quantity of zinc ; the difficulty of refining gold is also increased. 

 "When the object is to extract all the gold, it is advisable to use a small ex- 

 cess of zinc, as there are generally traces of other metals in the mercury 

 which interferes with the uniformity of the results. 



IMPROVEMENTS IX PUDDLING IRON. 



The following improvements in puddling iron have been patented in En- 

 gland, by James Nasmyth, the well-known inventor. The improvements con- 

 sist in the disengagement of the carbon from the molten metal in the puddling- 

 furnace, by subjecting it to the action of currents of steam, introduced as near 

 as possible at the lowest portion of the molten metal; thence diffused upward 

 so as not only to mechanically agitate the metal, and thereby expose fresh 

 surfaces to the action of the oxygen of the air passing through the furnace, 

 but also to remove the sulphur and other deleterious substances in the iron, 

 by thus making the oxygen of the air, and also the hydrogen of the water, 

 combine with and carry them off in the state of gas. It is stated that this 

 process shortens the period of puddling, and greatly improves the character 

 of the iron, rendering it tough and strong to a remarkable degree. The steam 

 is introduced by a pipe under the inolten metal, and the supply of it shut off, 

 when, in the judgment of the operative puddler, the metal has been suf- 

 ficiently decarbonized. The patentee states that water may be forced under 

 the surface of the metal to produce the same effects : but this would cause ex- 

 plosions ; small quantities, however, he says, would be equivalent to steam. 

 The steam is not used for about five minutes after the metal is melted. Care 

 must be exercised not to use it too long, or the oxygen of the steam will unite 

 with the iron and form an oxyd. 



IMPROVEMENTS IN THE MANUFACTURE OF TYPE. 



An English patent has been granted to J. K. Johnson for improvements in 

 the manufacture of type, which consist in employing tin in the place of lead, 

 mixed with antimony. The advantage gained is, that the type produced is 

 so hard, tough, and enduring, that they allow of being used as a punch on 

 the ordinary type-metal. Type so prepared preserve their faces sharp for a 

 great length of time, and in the end prove more economical than the cheaper 

 alloy of lead and antimony. The proportions used by the patentee are 75 

 parts of tin to 25 of antimony, but this may be to some extent varied. When 

 lead is also used, it must not exceed 50 parts in 100 of the combined metals 

 employed ; for if the lead be employed in much larger quantity an alloy is 

 formed which approaches ordinary type-metal in properties, notwithstanding 

 the presence of a large per centage of tin. Chemical Gazette, May 1, 1855. 



Another composition for type-metal has been recently patented in Bavaria. 

 The principal constituent is zinc to which the requisite properties are given 



