532 



Scientific Proceedings, Roijal Dublin Society. 



the theoretical volume of acetylene is 11'2 e.c, while in practice it has been 

 found that only 10'5c.c. are obtained. 



To standardize the apparatus the following experiment was carried out : — 

 Some sand was taken and tliorouglily ignited, and allowed to cool in a 

 desiccator. Afterwards the sand was weiglied out and a known weight of 

 water added. This was mixed with finely powdered carbide, and the volume 

 of acetylene was measured and reduced to normal temperature and pressure. 



These results are in accordance with those obtained by other observers from 

 different methods; and consequently lO'D c.e. of gas, equivalent to "018 grms. 

 of water, have been used in the calculations following. 



The hygroscopic moisture in a number of soils was determined both by the 

 carbide method and b_v the ordinary method of heating in the oven. The limit 

 of time for heating in the oven was fixed at sixteen hours, since it was found that 

 all normal soils had reached practically a constant weight in that time. The 

 samples used were a series of good arable soils, with the exception of one peat 

 soil and one sand containing no organic matter. The "fine earths" (material 

 less than 2 mm. in diameter) of the soils were used. 



From the above table it will be seen that, while the results by both 



