CH. xxxvn. JOHN D ALTON. 399 



and chlorine mixed together and placed in the sunlight 

 unite to form hydrochloric acid. 1 This method of bringing 

 elements together to form a compound substance is called 

 synthesis, and is exactly the opposite of analysts, or the 

 splitting up of a compound substance into its elementary 

 parts. 



To follow out the gradual development of synthesis and 

 analysis, and the discoveries of our great modern chemists, 

 such as Graham, Andrews, and others, would be to write a 

 work upon chemistry. There is only one other general prin- 

 ciple which we ought to try and understand here ; namely, 

 the proportions in which the elements combine to form sub- 

 stances. This principle, which lies at the root of all our 

 modern chemistry, was first worked out by a poor school- 

 master named Dalton. 



Dalton shows that the Different Chemical Elements 

 always Combine in Definite Proportions. John Dalton 

 was born of Quaker parents in 1766, near Cockermouth, in 

 Cumberland. He received the ordinary education of a 

 village school, and after being master of a small academy 

 at Kendal, he went to Manchester, where he supported 

 himself all the rest of his life by teaching mathematics. 

 Fortunately for science, a blind gentleman named Gough 

 became interested in him, and gave him the use of his 

 library and chemical laboratory, which enabled Dalton to 

 work out many useful facts, and to establish the laws which 

 are now the guide of all chemists, though they differ about 

 some of his conclusions. 



You will remember that it was only in the time of 

 Lavoisier that chemists began to weigh carefully the gases 



1 Sir H. Davy was the first to discover, in 1807, that hydrochloric 

 acid is made merely of hydrogen and chlorine ; before then it was 

 believed that every acid must have oxygen in it. 



