THE METALS PROPER, ETC. 1 



CHEMISTRY. 



371 



By means of a mixture of phosphorus, sulphur, and 

 chlorate of potass, the ordinary lucifer-match is made, 

 which, by mere friction, affords, as is well known, our 

 chief source of artificial light and heat. The following 

 experiment illustrates the production of light and heat 

 beneath water, by those materials. 



Fig. 62. 



Experiment 67. 

 luto a wine-glass 

 put a few grains of 

 chlorate of potass ; 

 fill up with cold 

 water, and then add 

 a few pieces of phos- 

 phorus. Through a 

 glass tube pour a 

 little sulphuric 

 acid; when this 

 reaches the bottom 

 of the glass, flame 

 will burst out. This 

 experiment requires caution, as sometimes the phos- 

 phorus flies out of the glass, and might injure the eye. 



The most important combination of phosphorus with 

 oxygen is that known as phosphoric acid : symbol, POi ; 

 equivalent, 72. This is produced by the combustion of 

 phosphorus in oxygen gas, and is of great importance in 

 animal economy. Combined with limn, it forms the 

 phosphate of that substance which, as we have already 

 shown, is an important constituent of the bones of 

 animals. Phosphoric acid combines with other bases 

 forming phosphates, such as those of soda, silver, <fcc. 

 The phosphates of lime are found in the excrements 

 and urine of animals ; and to their presence in guano, 

 together with nitrogen, the value of that substance as a 

 manure is due. With three equivalents of oxygen, 

 phosphorus forms phosphorous acid : symbol, POj ; equi- 

 valent = 56. This is produced when phosphorus under- 

 goes slow combustion in a limited amount of air. 



Phosphorus combines also with chlorine and iodine, 

 forming definite compounds ; which, however, do not 

 possess any special interest. 



Phosphoretted hydrogen gas is a compound of one 

 equivalent of phosphorus to three of hydrogen : symbol, 



Fig. 64. 



PH 3 ; equivalent = 35 ; and has the singular pro- 

 perty of spontaneous combustion. It may Fig. 63. 

 be readily prepared from the phosphide^ 

 of calcium, the latter being produced by heat- 

 ing together fresh-slaked liine with phos- 

 phorus, in a crucible or test-tube. If a piece 

 of the phosphide be put into a little* 

 warm water, beautiful rings of smoke are 

 formed, as represented in the annexed 

 figure. 



Phosphoretted hydrogen may also be pro- 

 duced by boiling a solution of potass and phosphorus 

 together in a Florence flask, to which a bent tube is 

 attached. The end of 

 the tube should dip 

 below the surface of 

 water ; and as the 

 smoke arises there- 

 from in rings, it drill 

 catch fire. An ar- 

 rangement suitable 

 for this purpose is 

 shown in the annexed 

 engraving. 



BORON. 



BOROH is an element of which little is known, in 

 a free state. Its symbol is B ; equivalent equals 10 '9 

 Combined with oxygen, however, it assumes consi- 

 derable commercial importance as boracic acid ; its com- 

 bination with soda forming the well-known borax. 

 Boron is prepared by heating boracic with potassium in 

 a test-tube, and, as such, is a green powder, which on 

 combustion again produces boracic acid. This acid may 

 also be procured by decomposing borax, by means of 

 sulphuric acid, which unites with the soda, setting the 

 boracic acid free. When this substance is dissolved in 

 spirits of wine, it affords a green colour during com- 

 bustion. Borax is largely employed by metallurgists and 

 chemists as a flux, and is particularly useful in blow-pipe 

 experiments. Boron unites with chlorine to form the 

 chloride of boron, and, with fluorine, it forms the fluoride. 



CHAPTER IV. 

 THE METALS PROPER, KALIGENEOtS, AND TERRIGENEOUS. 



ONE of the most difficult subjects in chemical science is 

 that of defining the exact character of a metal. So long 

 as the number of metallic bodies was confined to those 

 known by the ancients, no difficulty existed ; for the 

 properties of gold, silver, <fec. , are so distinct and marked 

 as to leave no doubt respecting them. During the early 

 part of this century, however, the discoveries of Sir 

 Humphry Davy brought to light metals which differed 

 entirely in their chief characters from those previously 

 known. Thus, for instance, potassium and sodium have 

 very low specific gravities compared with lead, iron, <kc. ; 

 they have very little tenacity ; cannot be drawn out 

 into a wire, or beaten into sheets ; and yet, from their 

 various qualities, no doubt can be entertained as to their 

 being properly termed metals. The same may be re- 

 marked in reference to calcium, magnesium, <ko. , which 

 form the basis of the earths, called Time, magnesia, &c. 

 In classifying bodies as metallic, we must have regard 

 to general rather than special properties ; and amongst 

 the former we may notice the tendency which all metals 

 have to combine with oxygen, chlorine, <tc. ; and of 

 forming salts with oxygen and acids. Generally speak- 

 ing, the metals are susceptible of receiving a high polish, 

 which they retain in proportion as they have little 

 affinity for the oxygen of air and water. Thus, platina, 

 gold, and silver, will maintain a polish on the surface for 

 almost any length of time ; whilst iron, lead, and zinc soon 

 become tarnished by oxidation. The tenacity of metals 

 differs exceedingly ; for whilst steel, gold, and silver may 



be drawn into wire finer than a human hair ; lead, tin, 

 etc. , can scarcely be drawn out at all. 



The uses of metals are so numerous and so well known 

 that we need scarcely refer to them ; but, perhaps, 

 amongst all, iron is of the greatest value to mankind. 

 Without it nearly every implement of manufacture 

 would be wanting ; and, strange to say, it is the most 

 abundant metal. It is a constituent of our bodies, 

 affording the colouring matter of our blood : it abounds 

 in plants and minerals ; and the colour of the earth and 

 rocks is frequently due to its presence. Within the last 

 few years a valuable addition has been made to our list 

 of useful metals, in the production of aluminum, which 

 is a constituent of common clay. For years its exist- 

 ence was recognised by chemists ; but to M. St. Claire 

 Deville, of Paris, and to the liberal patronage and aid of 

 the Emperor of the French, we are indebted for the 

 means of producing this metal in quantities. It is 

 highly probable that other metals, such as calcium, mag- 

 nesium, <tc., which at the present time are mere chemical 

 curiosities, will eventually, like aluminum, become of 

 use in the arts and manufactures. 



Considerable difficulty arises in properly classifying 

 metals for the purposes of describing them in groups. 

 This will be evident from the remarks we have already 

 made on their individual properties. In the following 

 pages wo shall divide them into three classes ; namely, 

 metals proper, kaligeneous. and terrigeneous. Amongst 

 the first are such as gol I, plaiiua, silver, &c. : in the 



