The President's Address. Btj H. C. Sorhy, F.R.8., &c. 115 



Now, if the gas containing the above-named number of atoms 

 consisted of two volumes of hydrogen to one volume of oxygen, 

 when combmed to form vapour of water there would be a condensa- 

 tion of volume from three to two, and on condensing into a liquid 

 a further contraction to yfo of the bulk of the vapour. Each mole- 

 cule of water would however consist of three atoms of gas, and hence 

 in order to determine the nmnber of molecules of liquid water 

 in ToW of an inch cube, it is necessary to multiply the number in 

 a gas by f X 770 x i = 385. This gives for the number of 

 molecules of water in toW inch cube about 3,972,000,000,000,000. 

 In this and all other cases I give round numbers, since any nearer 

 approximation is impossible. 



Though living organisms contain much water, yet far more 

 complex substances enter into their composition. As an example 

 of one of these, we may take albumen. According to Lieberkiihn 

 its composition is expressed by the formula C72Hii2Ni^SO.,2. It 

 therefore contains seventy-one times as many ultimate atoms as 

 water, and its atomic weight is about eighty-two times that of 

 water. In the condition of horn I find that its specific gravity is 

 about 1'31. Calculating from these data, I conclude that when 

 the various constituents combine they contract to fV of the total 

 volume, and not as water to f ; and that the volume of a single 

 molecule of albumen is about 55 • 6 that of a. molecule of liquid 

 water. If their form be similar, their diameter must therefore be 

 3 • 82 times that of a molecule of water. This would lead us to 

 conclude that in a cube of xioo of an inch of horn there are about 

 71,000,000,000,000 molecules of albumen. 



According then to these principles there would be in the 

 length of sowo of an inch about 2000 molecules of water, or 520 

 of albumen, and hence, in order to see the ultimate constitution of 

 organic bodies, it would be necessary to use a magnifying power 

 of from 500 to 2000 times greater than those we now possess. 

 These, however, for the reasons already given, would be of no use 

 unless the waves of light were some oyVo part of the length they 

 are, and our eyes and instruments correspondingly perfect. It will 

 thus be seen that, even with our highest and best powers, we are 

 about as far from seeing the ultimate constitution of organic matter 

 as the naked eye is from seeing the smallest objects which they now 

 reveal to us. Nor does there appear to be much hope that we ever 

 shall see the ultimate constituents, since light itself is manifestly 

 of too coarse a nature, even if it were possible to still further 

 develop our optical resources. As matters now stand we are about 

 as far from a knowledge of the ultimate structure of organic bodies 

 as we should be of the contents of a newspaper seen with the naked 

 eye at a distance of a third of a mile, under which circumstances 

 the letters of various sizes would correspond to the smaller and 



