ATOMIC THEORY. 415 



equivalent ; and two new salts are formed, without either loss 

 or addition in the act of change. A little consideration will 

 show that this single fact, well attested, discloses the whole 

 principle of definite proportions ; and the possibility by a 

 simple calculation of making a few analyses of such neutral 

 salts the key to others yet unmade. This principle was taken 

 up fifteen years later by Bichter ; who verified the facts, and 

 gave a tabular form to the reciprocal proportions or equiva- 

 lents thus obtained. 



The researches of Mr. Higgins, first published in 1791, 

 make a still closer approximation to those of Dalton, and 

 may seem to justify the claim of priority; put forward by 

 himself when the subject was yet fresh before the world, and 

 since urged by others on his behalf. There can be no doubt 

 that Mr. Higgins announced thus early, as he result of his 

 enquiries, certain conclusions which tally closely with those 

 obtained by Dalton ; as, for instance, that a molecule of water 

 is composed of one particle of oxygen united to one of hydro- 

 gen; that the five chemical compounds of oxygen and 

 nitrogen vary in the multiple proportions of oxygen added 

 to the single particle of nitrogen ; that sulphurous acid con- 

 tains one particle of sulphur with one of oxygen, sulphuric 

 acid two particles of the latter element. These conclusions, 

 since verified, are doubtless very remarkable ; the more so as 

 they seem to have been derived from imperfect data, and 

 without any clear conception of the great consequences they 

 involve. But whatever rank Mr. Higgins may finally take as 

 a discoverer, his researches fell at the time upon a heedless 

 world. We have before us conclusive evidence that Dalton 

 was ignorant of them until long after he had matured his 

 own doctrines. He read little ; thought and worked alone 

 in his laboratory ; and was too upright not to avow what 

 he got from another. His .yery nature made it impossible 

 for him to be a plagiarist. 



