When the potato famine occurred in Ireland in 1845-46, the disease was very prevalent in Hitcham. This induced the Professor to explain to his parishioners and others--for he published his recommendations--how they could utilise their rotten potatoes by extracting the valuable starch, which still remained sound within the tubers, even when these were refused by pigs. The process is so simple that it may be mentioned here. The potatoes must be _grated_ (a piece of tin with holes punched through it will do); the pulp is then stirred with a stream of cold water through a hair-sieve. The _brown_ water must be allowed a few minutes for the starch, carried through, to settle. The water is poured off, and the layer of starch must be stirred up and washed with fresh cold water. This may be done two or three times, till it becomes perfectly white. It must then be carefully dried in the sun or in a warm room (our method was to hang it up in small muslin bags in the kitchen); the bags must be repeatedly "kneaded" to prevent its clotting. When perfectly dry, it will keep for any length of time. Of course, it is precisely the same thing as sago, tapioca, cornflour, arrowroot, etc. and can be used like them. All our potatoes in the Rectory garden were rotten, but we recovered at least two sacks of starch. I remember taking a large sponge-cake to school, more or less made with this potato-flour, and making my reverend master somewhat incredulous by telling him it was made out of rotten potatoes!
Professor Henslow printed and circulated the receipt for the extraction of starch, in the village; so that several, who thought it worth while, obtained considerable quantities of starch.
In one of his lectures, dealing with this subject, he pointed out how a good basin of "arrowroot" can be made in ten minutes from two or three fair-sized potatoes; for as soon as the starch has been thoroughly "washed," it is ready for the boiling milk. It is essential the milk or water should be actually boiling, or the granules of starch do not burst and so make the required "jelly."
The school children of Hitcham were by no means left out in the cold as to the knowledge of natural phenomena. They were early instructed as to the harmless nature of toads and slow-worms, which were very abundant, on the one hand; and of the danger of handling a viper, on the other. This last is the only poisonous reptile in England, and easily recognisable by the lozenge-shaped marks down the back. Having specimens in spirit, they had no excuse for confounding them; but, as always happens with children, if there is an alternative of any sort between which they are well taught the difference, some one is sure to get them transposed in his memory. Consequently, a boy came up to the Rectory with his arm greatly swollen; he had been bitten by a viper which he had taken up, thinking it was a slow-worm, _because_, as he said, it had the marks along its back!