48 



CAPT. LL. LLOYD. 



Of the impurities tested, hexamethylene tetramine, methylamine and formic 

 acid were found to be of importance, and these only will be discussed. The efiects 

 of the presence of the other substances mentioned above were investigated and found 

 to be neutral, or of very little importance. 



Hexameihylene tetramine, {QH.^^^. 



This substance is produced by the action of ammonia on formaldehyde. It is 

 liable to occur in the solution owing to the presence of ammonia in the air during 

 manufacture. It breaks down with the formation of methylamine, CH3 NHg. 

 Formaldehyde containing these bodies has a yellowish colour and a fishy odour, 

 both these characteristics being intensified by the addition of a strong alkali. These 

 substances are distasteful to flies. A sample containing 5 grms. of hexamethylene 

 tetramine added per litre was tested against a control. The residue from the manu- 

 facture of this substance, containing ammonia and methylamine, and some methyla- 

 mine hydrochloride, with and without an alkali to set free the methylamine, were 

 also tested with the following results. 



Table I. 

 Showing the Influence of Hexamethylene tetramine in Formaldehyde, 



Solution 



Percentages of flies 

 killed 



Average 



9/ 



/o 



Total flies 

 kiUed 



Formaldehyde control, 10% 

 Formaldehyde with 5 grms. 

 hexamethylene tetramine 

 added per litre, 10% 



100 in each case 

 74, 130, 93, 71, 57 



100 



85 



324 



267 



Table II. 

 Showing the Influence of Methylamine in Formaldehyde. 



Solution 



Percentages 



of i 



^ies killed (actual 



numt 



ers 



in brackets) 



Formaldehyde control, 10% 



100 (50) 





100 (20) 



„ with 2-5% hexamethylene 









tetramine residue 1 % 



36 (18) 







,, with 1% hexamethylene 









tetramine residue 10% 







65 (13) 



„ with 1% methylamine 









hydrochloride 10% 







40 (8) 



„ with 5 % methylamine hydro- 









chloride and 0-2% KOH 









10% 



30 (15) 







,, with 1 % methylamine hydro- 









chloride and 01% KOH 









10% 







30 (6) 



A sample, naturally containing these substances in unknown proportion, with 

 a pale yellow colour and fishy odour (previously unsealed bottle from the store 

 of the Imp. Coll. Sci.) was tested against a colourless control with a clean odour. 



