clxx PROCEEDINGS—PERTHSHIRE SOCIETY OF NATURAL SCIENCE. 
what point of view to approach it. I shall therefore glance in turn 
at the progress which has taken place in each of the following 
sciences, namely:—Chemistry, Physics, Astronomy, Geology, and 
Biology. In other words, we shall enquire how much we know now, 
that we did not know sixty years ago, regarding matter, energy, the 
universe, the earth, and life. The first three I shall treat very 
generally, going into rather more detail with regard to the two last, 
as coming more within the scope of our Society. Lastly, I shall 
sum up the more important results which have accrued from the 
increase in our knowledge of Nature and her laws. 
I.—CHEMISTRY. 
By the time the Queen ascended the throne, the foundations of 
modern chemistry had been securely laid. Before the beginning of 
the present century, indeed, Lavoisier had laid down the lines 
of study which all subsequent workers have followed, including 
the recognition of the three forms of matter,—gaseous, liquid, and 
solid.—the division of chemical substances into elements and com- 
pounds, and the indestructibility of matter. Then, in the early years 
of the present century, following the labours of Black, Cavendish, 
and Priestley, Dalton had enunciated the Atomic Theory, on which 
so much recent progress has been based, and Sir Humphrey Davy, 
amongst many other services to the science, added a new method of 
research by his discovery that an electric current has the power of 
decomposing certain substances. It was just about the beginning of 
the Queen’s reign that Davy’s work was taken up and carried forward 
by Sir Michael Faraday, who demonstrated still further the relation 
between electricity and chemical affinity. 
Curiously enough, two substances of immense importance in our 
modern life were discovered just a few years before the beginning of 
the reign, but were not put to their present uses till several years 
later. In 1825 Faraday discovered aniline, and in 1832 Liebeg 
discovered chloroform; but it was not until 1856 that Perkins 
showed what an infinite variety of colouring matter can be got from 
the former, and it was not until 1847 that Sir J. Y. Simpson applied the 
latter for the amelioration of human suffering. In these two incidents 
we have striking examples of the infinite uses which often arise from 
studies which, to the popular mind, appear useless in themselves. 
Science has always proceeded on the assumption that truth is worth 
pursuing for her own sake alone, and from this pursuit results of the 
most stupendous and beneficent character have constantly flowed. 
During the reign our knowledge of the gases and their properties 
has advanced greatly. In the earlier years of it Thomas Graham 
formulated the Law of the Diffusion of Gases, and more recently 
some startling results have been achieved in the liquefaction of what 
were formerly supposed to be “ Permanent Gases,” chiefly through 
the labours of M. Pictet and M. Cailletet. Thus, in 1877, first 
oxygen, then nitrogen, and lastly atmospheric air, were liquefied.* 
* Until quite recently, it was thought that hydrogen had been liquefied, and 
even solidified, at the same time. It was not until May, 1898, however, that 
Prof. Dew T ar succeeded in liquefying hydrogen, and finally helium. 
