248 



MAJOR J. H. MANSELL: INVESTIGATION OF 



The cubical form of this equation is of interest when one compares it with 

 VAN DER WAALS' general equation 



^ (v-6) = KT, 



V vf 



which may be written 



p (1-6A) = a&A 3 -aA 2 +RTA. 



It would appear, then, that in any general deduction of a pressure-density relation 

 from VAN DER WAALS' equation omission of the term afv* is not justified. PETAVEL 

 neglected this term in his investigation of Mark I cordite.* 



Tonkin? 

 2.0 



19 

 18 

 17 

 16 



15 

 14 

 13 

 12 

 II 

 IO 

 9 



e 



7 

 6 

 5 

 4 

 3 

 z 

 I 



Cord 



M.D. at A 



-4 



Z446 



D 



1265 



a 



e 



A 



o Points as measured off Che 'record . 



J 



calculated by Che reduction table. 



: Tube 



Points as 

 the 



M.D. at A 



measured 

 record. 



calculated 



0-16935" 

 0-07315" 



allowing for excess internal 

 Batch. 89. 



pressure 



OOI 



OO2 



OO3 



004 -005 



006 



007 -008 -009 



Time- Seconds 



oio 



on 



012 



013 



014 



015 



Fig. 4. Time rise of pressure, cord and tube M.D. 



Cordite in manufacture is made in lots, and the above pressure-density relation is 

 true of the general run of the cordite. In the earlier stages of the manufacture of 

 some experimental forms of M.D. cordite the pressure-density relation was different. 

 This may have been due to slightly different chemical constitution, to the presence of 

 an excess quantity of volatile matter, or to minor variations in manufacture. The 

 point is unimportant, because with experience in manufacture this variation dis- 

 appears; but I mention it, as in one of the experiments I shall refer to later such an 



* ' Phil. Trans., A, vol. 205, pp. 357-398. 



OI6 



