It is common knowledge that blood constitutes a magnificent fertilizer, and this is the purpose to which the dried clot is applied. In a well-designed vacuum drying plant, such as the Scott, which has been designed especially to treat such residue, the efficiency is high. The yield from the clot may be said to range from 25 to 30 per cent.--560 to 672 lb.--per ton of raw clot treated, and is recovered in the form of a rich red dry powder. One great objection levelled against the recovery of the blood for fertilizing purposes has been the very offensive odour which is thrown off during the drying operation. But when the task is conducted under the vacuum system no such nuisance is created, because the obnoxious gases are led to the fire to suffer combustion. In dryers of the conventional type, in which the noxious gases are removed by the aid of an exhausting fan, or suffer discharge into the chimney, the process does represent an intolerable nuisance to the neighbourhood, because there is nothing to prevent the pollution of the atmosphere. Furthermore, and this is the most important point to remember, by drying the blood under the vacuum system the ammonia content of the waste, which normally is high, can be preserved to the full, owing to the drying operation being carried out at a much lower temperature than is incidental to the usual practice. Dried blood appeals to the farmer for the nourishment of his land essentially because of its pronounced proportion of nitrogen or ammonia. Consequently it is incumbent to keep this figure as high as possible and thus secure the advantages of market quotation. Naturally the percentage thereof in the resultant meal will vary strikingly according to the drying process practised. Ammonia is an exceedingly volatile ingredient, its tendency to escape being accentuated as the temperature employed is increased. It is only by keeping the heat factor at a low level consistent with the complete fulfilment of the desired operation, that the ammonia can be retained. Under the vacuum system this end is assured, owing to the low boiling-point due to the reduced pressure or vacuum. A typical analysis of vacuum-dried clot blood may be cited:-- Per cent. Moisture 9 Mineral matter 1·61 Nitrogen 14·02 ⤷ = ammonia 17·02 In cases where the albumen is not required separately the whole blood is dried without being separated or “clotted.” It is obvious from what I have related, that the recovery of by-products from what has always been regarded as waste of a most repulsive character, that is from the popular point of view, can be turned to striking commercial and industrial account. Similarly it is only too apparent that such by-product reclamation as is possible demands a plant of the most complete description, to ensure all and every substance of utilitarian value being secured along the most efficient lines and to the uttermost ounce.