OXYGEN. b 



not actually made in vacuo, but were, nevertheless, reduced 

 to a vacuum standard. The second series represents actual 

 vacuum weighings. The quantity of water formed in each 

 experiment, was from 41.664 to 95.612 grammes. I give 

 below only the percentages of oxygen and hydrogen in 

 water as deduced from Erdmann and Marchand's data : 



The effect of discussing these two series separately is 

 sOmewhat startling. It gives to the four experiments in 

 Erdmann and Marchand's second group a weight vastly 

 greater than their other four and Dumas' nineteen taken 

 together. For so great a superiority as this there is no 

 adequate reason ; and it is highly probable that it is due 

 almost entirely to fortunate coincidences, rather than to 

 greater accuracy of work. We will, therefore, treat Erd- 

 mann and Marchand's experiments as one series, giving all 

 equal weight, and then combine them with the results ob- 

 tained by Dumas. We now have — 



