182 THE VITAMINS 



Later Zilva (1924) prepared a still more concentrated extract by 

 evaporating the decitrated lemon juice to one-tenth of its volume and 

 acidifying it by the addition of seven grams of citric acid to one liter 

 of juice. No loss in potency of this product could be detected after 

 storage under laboratory conditions in a dark cupboard for five months. 

 The concentrated product was also used after six months' storage in 

 the treatment of a very severe case of infantile scurvy. The treatment 

 was very intensive, the equivalent of about fifteen lemons being given 

 during the first twenty-four hours. The patient was discharged cured 

 in ten days after the equivalent of about forty-eight lemons had been 

 administered. Decitrated lemon juice has been used to a considerable 

 extent as the basis for the preparation of concentrates for prophylactic 

 and therapeutic treatment and also in experimental work on the anti- 

 scorbutic vitamin. 



Another method of preparing a lemon juice concentrate in con- 

 venient form was described by Bassett-Smith (1920). The fresh juice 

 is filtered through muslin and then through filter paper under reduced 

 pressure. The filtered juice is evaporated in vacuo over sulfuric acid 

 at ordinary temperature and the sirupy residue made into as stiff a 

 paste as possible with a mixture of 97 per cent anhydrous lactose and 

 3 per cent gum tragacanth. The paste is cut into sections, each con- 

 taining the juice of half a lemon. These are then rolled and pressed 

 into the shape of lozenges. Experiments were reported in which these 

 tablets were used both for the prevention and for the cure of scurvy 

 in guinea pigs with excellent results, one-fifth of a tablet, equivalent 

 to 4.8 cubic centimeters of fresh lemon juice, representing the mini- 

 mum preventive dose. It was estimated that one tablet, the equivalent 

 of half a lemon, would be ample as a daily dose to prevent scurvy in 

 adult human beings. 



As these tablets have been found to retain their antiscorbutic proper- 

 ties for over a year when stored at room temperature (Bassett-Smith, 

 1920a, 1921) they afford an antiscorbutic of small bulk eminently 

 suited for long voyages. Macklin and Hussey (1921) state that the 

 antiscorbutic substances used on board ship in the Shackleton polar 

 expeditions included lemon juice concentrated by this method but not 

 made into tablets, while for sledging conditions lemon juice tablets 

 are used. 



Harden and Zilva (1918) also made use of orange juice in their 

 studies of the behavior of antiscorbutic substances. On treating a mix- 

 ture of autolyzed yeast and orange juice with various adsorbents and 

 testing the filtrates on polyneuritic pigeons and scorbutic guinea pigs, 



