258 Mr. J. J. Waterston on Chemical Notation. 



bined with half a gas-molecule of hydrogen ; or it has nothing 

 to do with ethyle, but is a primary hydrocarbon isomeric if not 

 identical with methyle. Marsh-gas, called hydride of methyle, 

 has its molecule composed of half a gas-molecule of methyle 

 united with half a gas-molecule of hydrogen ; or it has nothing 

 to do with methyle, but is a primary hydrocarbon. 



Zincethyle has vapour-density 61*5, showing that a vapour- 

 molecule is composed of 32*5 zinc, 24 carbon, and 5 hydrogen. 

 If it is a primary compound of one molecule zinc with one of 

 ethyle, the combining affinity of the elements for oxygen must 

 in consequence be much exalted, because it takes fire instantly 

 on coming in contact with the air. Or it may be viewed as a 

 secondary compound of a metallic hydride with etherine. There 

 is at least one metallic hydride, the hydride of copper, which 

 presents the same exaltation of affinity in respect to chlorine. 

 Its composition is 1 hydrogen to 64 copper, or £ to 32, which 

 gives the formula H^Cu. When treated with muriatic acid, 

 CI* H 7 , the H 7 of the cupride unites with the H 7 of the acid to 

 form H, which is the hydrogen evolved, and the Cu unites with 

 the CI* to form the dichloride of copper, CI* Cu. This action is 

 stated to be very remarkable (Graham, vol. ii. p. 96), inasmuch 

 as metallic copper is scarcely acted on by muriatic acid ; i. e. Cu 

 and H^ CI 7 are passive, while Cu H* and CI 7 H 5 are intensely 

 active. At p. 517 there is the following remark : — "To reduce 

 these bodies (viz. the elementary) to the same standard, it is 

 necessary to assume that each molecule of an elementary body 

 in the free state consists of two elementary atoms." And at 

 p. 517, "It appears indeed as if [such] atoms could not exist in 

 a state of isolation. An atom [i. e. O 7 , H 7 , CI 7 , &c] of an ele- 

 mentary body must unite either with an atom of another element or 

 with one of its own kind" We thus may see the propriety in 

 every way of viewing them and expressing them as fractions of 

 a molecule : with such symbols the peculiar action of the hydride 

 of copper on muriatic acid no longer appears remarkable. 



In the case of zincethyle, considered as composed of a hydro- 

 carbon C 2 H 4 (etherine) and a metallic hydride, the latter must 

 be Zn combined with H, a whole gas-molecule of hydrogen. 

 The action on being presented to the atmosphere is ZnH pre- 

 sented to of the atmosphere, i. e. to whole gas-molecules of oxy- 

 g en — causing, with their exalted affinity, the division O 7 0% one 

 of which burns with Zn, forming the protoxide of zinc, ZnO 7 ; 

 the other burning with H to form water, HO 7 . 



The apparent exaltation of affinity in these and other similar 

 cases may be caused simply by the atoms of metal existing un- 



