356 



Wi7iter Cotter Washes 



The following mixtures were tried with the results included in the 

 table below: 



Aluminium Copper 



Result 



Thick coating when wet, very 



hard and firm when dry 

 Thick coating when wet, but not 



quite so good when dry as (1) 

 Decidedly thinner when wet and 



powdery when dry 

 Thin when wet and loose when 



dry 



The addition of glue did not improve the mixture, and copper sulphate 

 again caused thinning and loss of adhesiveness. 



Substitution of alum for aluminium sulphate. 



It being possible to obtain alum at l^d. a pound while the cheapest 

 quotation for aluminium sulphate is 2|(?., the former was tried in its 

 place. At the same time iron sulphate was introduced as a fungicide 

 with the results given in the following table: 

 Alum 



Unlike the copper sulphate, iron sulphate does not cause a thinning 

 of the mixture. 



In order to test the rain resisting power of the various mixtures 

 that had been made up, slides covered with them were soaked in water 

 for 24 hrs. The mixtures and results are given in the following table : 



No. 



(1) 

 (2) 

 (3) 



(4) 

 (5) 

 (6) 

 (7) 



Lirae 



2 



14 

 20 



Whit- Dichro- Iron Cressyllic Residt after 



ing Alum Farina Glue mate sulphate acid Water 24 hrs. soaking 



— ^ — — — -f\ — 10 Very good. Still hard 



8 — i i TiV 



8 - i i ^\ 



7 — 1 1 i 

 ______ 5 



8 - i ^ _ _ _ 



- - 10 



— — 80^ 



10 

 10 

 80 



100 Poor 

 10\ 



Resisted fairly well 



lOj 



Very poor 



The mixtures in this table were subsequently tested in the field 

 (see Field experiments, 1913-14) when it was found that No. (2) gave 

 by far the best results. As, however, the whiting therein cost as much 

 as l^d. in the total of 2d. per gallon of wash, it was necessary to try 

 whether lime could be substituted instead. At the time the fact 



