THE NEW CHEMISTRY, A DEVELOPMENT OF THE OLD. 115 
spherical hollow balls inside out without tearing or breaking 
them ! 
While we look forward to the future of science with hope, I 
think we ought not to look back on the former workers without 
respect. 
But I must pass on to consider the second of the great 
theories which have paved the way for the doctrines of modern 
chemistry. The germ of the modern ideas of substitution, 
valency, atom-linking, &c., is, I believe, to be found in the 
pure dualism of Berzelius, and moreover, the influence of the 
dualistic ideas of that great chemist seems to me easily trace- 
able in the essentially unitary system of modern chemistry. 
The chemistry of Lavoisier centred around the wonderful 
substance whose properties he so carefully studied. The 
teaching of the great founder of modern chemistry was satu- 
rated with ideas suggested by the study of oxygen. The 
compounds of oxygen were divided by Lavoisier into two 
groups, bases and acids : when these reacted chemically, a 
salt — that is, a body made up of base and acid — was produced. 
Berzelius developed these ideas until he had constructed a 
complete and beautiful theory, viewed in the light of which 
all compounds were of analogous structure. Every chemical 
substance was made up, according to the Swedish chemist, of 
two parts ; these parts might themselves he composed of simpler 
parts, or they might be truly elementary. The two parts of a 
compound were respectively endowed with positive and negative 
electricity. When two bodies combined the positive electricity 
in one neutralized the negative electricity in the other ; hence 
the phenomena of light and heat noticed in chemical com- 
bination. An element might contain an absolutely greater 
quantity of positive electricity than another and nevertheless 
belong to the electro-negative series of elements : thus sulphur 
and oxygen readily combine to form a substance which r when 
dissolved in water, yields an acid. But oxygen and sulphur are 
both electro-negative elements. Berzelius supposed that sulphur 
contained a large quantity of both electricities, the negative 
predominating. When this element combined with oxygen, 
the positive electricity of the sulphur was supposed to be 
neutralized by the negative electricity of the oxygen, so that 
the negative electricity of the sulphur was concentrated or 
rendered more apparent. The affinity between oxygen and 
silver is less than that between sulphur and oxygen, because, 
said Berzelius, silver contains mainly positive electricity, but a 
smaller quantity than is found in sulphur. The product of the 
union of oxygen and sulphur, i.e ., of oxygen with an electro- 
negative body, belongs to the class of acid oxides ; the product 
