G. Williams 183 



The present paper deals with the soluble protein contained in the 

 juice. 



Preparation of the Protein. 



The swedes used were fairly well-grown specimens freshly pulled 

 up from the ground at various times during the winter ; they were quite 

 free from any signs of disease. They were cleaned and washed to remove 

 adherent soil particles, and then passed through a shredding machine. 

 The juice was squeezed out by means of a press, the average amount 

 obtained being about 40 per cent, of the weight of shreds taken. The 

 turbid juice was filtered through ordinary filters and was then obtained 

 as a transparent slightly dark-coloured liquid. Fresh filters had to be 

 used every other day owing to the rapid growth of acid-producing 

 bacteria, causing precipitation of the protein before filtration. The 

 clear filtrate was heated in beakers up to 90° C. for about half an ho.ur, 

 which served to precipitate all the protein as a practically white curdy 

 mass. The precipitate was allowed to settle, and then the supernatant 

 liquid was carefully poured off. The beakers were filled up with 

 hot distilled water, and the protein allowed to settle again, whereupon 

 the water was poured off as completely as possible. The protein was 

 washed seven times with hot distilled water in this manner. It was next 

 washed three times with alcohol by decantation, and finally ether was 

 poured on to it. Great economy of alcohol was effected by carrying 

 out the washing in the vessels of a large centrifuge. The ether was 

 filtered off on a Buchner funnel, and the protein washed on the filter 

 twice with ordinary ether, and finally with anhydrous ether. It Avas 

 then placed in a vacuum desiccator over sulphuric acid ; it soon dried 

 to a light grey mass which was easily ground down to an impalpable 

 powder in a mortar. After heating in a water oven for two or three 

 days it ceased to lose weight. 



One lot of six litres of the clear filtered juice treated as described 

 above gave 9 grams of dry protein. This represented a yield of 0-15 

 gram of protein from 100 c.c. of juice. 



One preparation obtained in this manner contained 



14-09 per cent, nitrogen (determined by the Dumas and Kjeldahl 



methods), 

 1-81 per cent, water, 

 8-60 per cent, ash, 

 the percentage of nitrogen in the dry ash-free substance thus being 



