204 SCIENCE AND FRUIT GROWING 



Emulsions with Mortality 



i per cent, soap and of eggs. 



1 per cent, paraffin o per cent. 



2 . O 



4 ,,;,,, o ,, 



6 ... 15 



8 . 13 



10 ,, . 40 



15 . 43 



Following the indications already obtained in other cases, it 

 was considered possible that, whilst a moderately strong emul- 

 sion, and also an alkaline solution, might both be ineffective 

 separately, yet when acting together the results might be satis- 

 factory. At that time the emulsifying powers of the basic sul- 

 phates of iron, etc., had not been ascertained, and the emulsions 

 used were made with soap. The addition of alkali to these 

 separated soda-soap, and the emulsion was converted into a 

 quasi-emulsion (see p. 159), which could not be applied so satis- 

 factorily as a true emulsion : yet in spite of the irregularities 

 attributable to such a cause, the general results showed con- 

 siderable uniformity. Thus 



Emulsion with 



i per cent, caustic soda Mortality 



and of eggs. 



2 per cent, paraffin ... 3 per cent. 



4 ,. - 20 



6 ... 74 



8 ... 60 



10 ,, . 73 



15 . 99 >. 



The 6 per cent, paraffin emulsion by itself, according to the 

 results previously quoted, caused a mortality of only 15 per 

 cent., and the i per cent, solution of caustic soda by itself caused 

 no mortality at all (p. 201), but the two together caused a 

 mortality of 74 per cent. ; and this probably understates the 

 true effect, for in 12 out of the 17 sets of observations on which 

 this value depends, the mortality was complete, the mean value 

 being pulled down by five cases where exceptionally low values 

 were obtained, doubtless, owing to the difficulty in applying a 

 quasi-emulsion satisfactorily. The efficiency in all these cases 

 was also under-estimated from the cause mentioned on p. 207. 



Various subsidiary questions in connection with these caustic 



