Oxide. Carbonic Anhydride, and Nitrous Oxide. 205 



supply of alkali was required. A wash -bottle and a long nearly 

 horizontal tube contained strong alkaline solution, and these were 

 followed by the tubes containing solid potasli and phosphoric anhyd- 

 ride as before. 



For the experiments of the third set oxalic acid was replaced by 

 formic, which is more convenient as not entailing the absorption of 

 large volumes of C0 2 . In this case the charge consisted of 50 grams 

 formate of soda, 300 c.c. strong sulphuric acid, and 150 c.c. distilled 

 water. The water is necessary in order to prevent action in the 

 cold, and the amount requires to be somewhat carefully adjusted. 

 As purifiers, the long horizontal bubbler was retained, and the tubes 

 charged with solid potash and phosphoric anhydride. In this set 

 there were four concordant experiments. The immediate results 

 stand thus : — 



Carbonic Oxide. 



From ferrocyanide 2*29843 



,, oxalic acid 2'29852 



„ formate of soda 2*29854 



Mean 2-29850 



This corresponds to the number 2*62704 for oxygen,* and. is subject 

 to a correction (additive) of 0*00056 for the diminution of the 

 external volume of the globe when exhausted. 



The ratio of the densities of carbonic oxide and oxygen is thus 

 2*29906 : 2*62760 ; so that if the density of oxygen be taken as 32, 

 that of carbonic oxide will be 27*9989. If, as some preliminary 

 experiments by Dr. Scott f indicate, equal volumes may be taken as 

 accurately representative of CO and of 2 , the atomic weight of 

 carbon will be 11*9989 on the scale of oxygen = 16. 



The very close agreement between the weights of carbonic oxide 

 prepared in three different ways is some guarantee against the 

 presence of an impurity of widely differing density. On the other 

 hand, some careful experiments led Mr. T. W. Richards']: to the 

 conclusion that carbonic oxide is liable to contain considerable quan- 

 tities of hydrogen or of hydrocarbons. From 5J litres of carbonic 

 oxide passed over hot cupric oxide he collected no less than 25 milli- 

 grams of water, and the evidence appeared to prove that the hydrogen 

 was really derived from the carbonic oxide. Such a proportion of 

 hydrogen would entail a deficiency in the weight ;of the globe of 

 about 11 milligrams, and seems improbable in view of the good 

 agreement of the numbers recorded. The presence of so much 



* " On the Densities of the Principal Gases," 'Koy. Soc. Proc.,' vol. 53, p. 144. 

 f ' Camb. Phil. Proc.,' vol. 9, p. 144, 1896. 

 X ' Amer. Acad. Proc.,' vol. 18, p. 279, 1891. 



