Absorption of Hard X-Rays in the Lightest Elements. 1Z1 



When the molecular absorption coefficient for H 2 is taken 

 equal to one, we obtain, from the above organic compounds, 

 values of absorption coefficients of C and H in various com- 

 pounds in different proportions. If these values are treated 

 by the least square method, we obtain the values, recorded in 

 Table II J ., of the absorption coefficients of C and H in relation 

 to water (a:h/h 2 o? ^c/h o)? an d by means of the value «h/h 2 o, 

 we obtain the corresponding value of (ko/b 2 o), when, as 

 stated above, the molecular absorption coefficient of H 2 is 

 taken equal to one. It is from the observed values of /ca/h 2 o 

 for N 2 H 4 that the relative atomic absorption coefficient of 

 N (tfff/H 2 o) nas then been calculated. 



Table III. — The atomic absorption coefficients of H, C, N, 

 and in relation to the molecular absorption 

 coefficient of H 2 0. 



I. II. III. IV. V. VI. 



«.„,„„ 0-068 0-081 0088 0-093 0-096 0-098 



0-504 0-532 0-547 0-560 0572 0-575 



*C/H 2 



0-874 0-838 0-824 0-814 0*808 0-804 



K „ lirn 0-663 0-675 0-674 0-683 0-684 0-685 



#0/H 2 



By the method used before, i. e. by the aid of the difference 

 between the molecular absorption coefficients of pairs of 

 compounds, which in chemical respect differ only by one or 

 more atoms of oxygen, the following mean values for /co/h 2 o 

 will be obtained : — 



I. II. III. IV. V. VI. 



ko/h,o...0-86 0-85 0-83 0*81 0'79 0*78 



These values agree very closely with those recorded in 

 Table III., yet they must from the reason stated above be con- 

 sidered less certain than those last mentioned. If not only 



KlLH.o and *c/H 2 bLlt *°/ H 2° ^ tlie ai<l ° £ the leaSt S( l Uare 



method is directly calculated from the values of at A /h 2 o of the 

 examined compounds of H, C, and O (Table II.), values 

 are obtained, which inconsiderably differ from those given in 

 Table III. The probable errors of the coefficients found 

 calculated by the said method reach, for /c H h,o a mean of 



4 per cent., and for /c C /h 2 o ar, d *o/h 2 o 1 P er cent - 

 The atomic absorption coefficient of a certain el 



ement can 



