100 



salts as magnesium lactate have a stronger antiseptic effect. 

 Lactic acid, together with common salt, hinders the development 

 of moulds though not to a great extent. 



A solution of o.i ^/^ benzoic acid prevents the growth of 

 moulds; with 15^/0 of common salt 0.05'^/^ is sufficient. 



Sodium benzoate has much less preservative effect ; 2 "/^j is 

 not sufficient to suppress the growth of Pénicillium and Clado- 

 sporium completely; when 15 **/(, of common salt is added how- 

 ever, 0.5 "/o suffices. 



Boric acid is an effective poison for Pénicillium and Oidium 

 but not for Cladosporium. This latter develops fairly well in 

 solutions with 10 "^/^ of salt and 2.5 "/^ of boric acid. 



Borax is a much better preservative than boric acid owing 

 to its alkaline reaction. Cladosporium does not grow in solutions 

 with 10 ^/ Q of salt and 0.1 "/^ of borax. 



o. Toluylic acid as a preservative is inferior to benzoic acid, 

 whereas cinnamic acid proved to be a strong poison for Clado- 

 sporium ; it is not so strong however for Pénicillium. 



As in practice only benzoic acid, sodium benzoate, boric acid 

 and borax come into consideration as preservatives, these were 

 subjected to further examination. 



This brought to light that vegetable margarine is only , well 

 preserved when so much salt and other preservatives are dis- 

 solved in the waterdrops contained in the margarine {in chur- 

 ning, these drops are minutely and eçtially divided), so that 

 the growth of the most dangerous ?noulds (e.g. Cladosporium) 

 is quite impossible. In this respect therefore the water percen- 

 tage of the butter plays an important part. As the percentage 

 becomes higher, more preservatives must be added in order to 

 preserve the margarine satisfactorily. Further, part of the %alt 

 and the preservative is always withdrawn from the solution in 

 water because it is either enveloped by the fat or perhaps 

 becomes partly dissolved in it (e, g. benzoic acid.) With borax, 

 boric acid and sodium benzoate however, the greater part is 

 traced in the aqueous part of the butter, whereas benzoic acid 

 may combine with the albumen of the milk, which is still 

 present in the butter. On the whole, experiments pointed out 

 that the quantity of preservative required in order to keep 

 margarine fresh is larger than one would infer from experi- 



