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 Dr Wiley’s conclusions were adversely criticized by Dr O. Liebreich, who carefully studied on the spot all the conditions of the experiment and the documents relating to the investigation. He pointed out that the results were so indefinite and the number of persons under control so small that “one case of self-deception or of forgetfulness only would throw into absolute uncertainty the solution of the whole question”; that no lasting injury to health was found in spite of transient disturbances attributed by Dr Liebreich to other causes, and that all persons declared themselves to be in better physical condition after seven months than they had been before. On the whole the balance of evidence seems to be that while no acute injury is likely to result from boron compounds in food, they are liable to produce slighter digestive interferences.

Other chemical substances that are in use for the purpose of preserving food materials may be treated more shortly. Formaldehyde, coming into commerce in the form of a 40% solution under the name of formalin, was for a time largely used in milk. It certainly has very great antiseptic properties, as little as 1 part in 50,000 parts checking the growth of organisms in milk for some hours, but as the substance combines with albuminous matters and hardens them to an extraordinary degree, rendering, for instance, gelatine perfectly insoluble in water, it exerts an inhibitory effect on the digestive ferments. It injures salivary, peptic and pancreatic digestion. A set of five kittens fed with milk containing 1 part in 50,000 of formaldehyde for seven weeks were strongly retarded in growth, three ultimately dying, while four control kittens fed on pure milk flourished. In even moderate doses formalin produces severe pains in the abdomen and has caused death. It is now generally recognized as a substance that is admirably adapted for disinfecting a sick-room, but quite improper and unsuitable for food preservation.

Salicylic acid or orthohydroxybenzoic acid is either obtained from oil of winter-green or is made synthetically by Kolbe’s process from phenol and carbonic acid. Artificial salicylic acid generally contains impurities (creasotic acids) which act very injuriously upon health. When pure, salicylic acid employed as a food preservative has never produced decided injurious effects, although administered by itself in fairly strong solution it acts as an irritant to the stomach and kidneys, and sometimes causes skin eruptions. It is a powerful drug in larger doses and requires careful administration, especially as about 60% of the persons to whom it is administered show symptoms known as “salicylism,” namely, deafness, headache, delirium, vomiting, sometimes haemorrhage or heart-failure. It is doubtful whether pure salicylic acid produces these symptoms. When present in proportion of 1 to 1000 it inhibits the growth of moulds and yeasts. In jams 2 grains per pound and in beverages 7 grains to a gallon are considered by manufacturers to be sufficient for preservative purposes. It is used mainly in articles of food or drink containing sugar, that is to say, in jams and preserved fruit, lime and lemon juices, syrups, cider, British wines and imported lager. Its use in butter, potted meat, milk or cream, in which it was not infrequently met with formerly, is now quite exceptional. It has already been stated that the preservative committee recommended its permissive use in small proportions. To some extent benzoic acid and benzoates have taken the place of salicylic acid and salicylates, partly because salicylic acid can readily be detected analytically, while benzoic acid is not quite easily discoverable. Its antiseptic potency is about equal to that of salicylic acid, and the arguments for or against its use are similar to those relating to the latter.

For the preservation of meat and beer, lime juice and dried fruit, sulphur dioxide (sulphurous acid) and some of the sulphites have long been employed. Sulphuring of hops and disinfection of barrels by burning brimstone matches is an exceedingly old practice. Burning sulphur is well known as a gaseous disinfectant of rooms, bacteria being killed in air containing 1% of the gas. As the taste and smell of sulphurous acid and of sulphites are very pronounced it follows that but small quantities can be added to food or drink. About 1 part in 4000 or 5000 of beer is the usual amount. While, in larger quantities, the sulphites have decided physiological activity and are apt to produce nephritis, there is not any evidence that they have ever caused injurious effects in alcoholic liquors. The excise authorities have tacitly sanctioned their employment in breweries, although the Customs and Inland Revenue Act 1885 declares that a brewer of beer shall not add any matter or thing thereto except finings or other matter or thing sanctioned by the commissioners of Inland Revenue, and although sulphites are used in all breweries, the Board of Inland Revenue do neither sanction nor interfere. An antiseptic with a pronounced taste is obviously a safer one in the hands of a non-medical person than one virtually devoid of taste, like boric, salicylic or benzoic acids or their salts.

Sodium fluoride, a salt possessing powerfully antiseptic properties, but also at the same time clearly injurious to health and interfering with salivary and peptic digestion, has been found in butter, imported mainly from Brittany, in quantities quite inadmissible in food under any circumstances. A few other chemical preservatives are occasionally used. Hydrogen peroxide has been found effective in milk sterilization, and if the substance is pure, no serious objection can be raised against it. Saccharine, and other artificial sweetening agents, having antiseptic properties, are taking the place of sugar in beverages like ginger-beer and lemonade, but the substitution of a trace of a substance that provides sweetness without at the same time giving the substance and food value of sugar is strongly to be deprecated.

The employment of chemical preservative matters in articles intended for human consumption threatens to become a grave danger to health or well-being. Each dealer in food contributes but a little; each one claims that his particular article of food cannot be brought into commerce without preservative, and each condemns the use of these substances by others. There is doubtless something to be said for the practice, but infinitely more against it. It cheapens food by allowing its collection in districts far away, but the chief gainer is not the public as a whole but the manufacturer and the wholesale merchant. Our body has by inheritance acquired habits and needs that are quite foreign to chemical interference. Some day, artificially prepared foods, containing liberal quantities of matters that are not now food ingredients, may conceivably compare with natural food products, but that day is not yet, and meantime it ought to be clearly the duty of the state to see that the evil is checked. The intention which has introduced this form of adulteration may be more or less beneficent, but in practice it is almost wholly evil.

A similar criticism applies to the continually extending use of colouring matter in food. Civilized man requires his food not only to be healthy and tasty. but also attractive in appearance. It is the art of the cook to prepare dishes that please the eye. This is a difficult art, for the various colouring matters which are naturally present in meat and fish, in fruit, legumes and green vegetables are of a delicate and changeable nature and easily affected or destroyed by cooking. Many years ago some artful, if stupid, cook found that green vegetables like peas or spinach, when cooked in a copper pan, by preference a dirty one, showed a far more brilliant colour than the same vegetables cooked in earthenware or iron. The manufacturer who puts up substances like peas in pots or tins for sale produces the same effect which the cook in her ignorance innocently obtained, by the wilful addition of a substance known to be injurious to health, namely, sulphate of copper. The copper combines with the chlorophyll, forming copper phyllocyanate, which, by reason of its insolubility in the gastric juice, is comparatively innocuous. Preserved peas and beans have been for so many years “coppered” in this manner that it is difficult to induce the public to accept these vegetables when possessed of their natural colour only. Several countries endeavoured to abolish the objectionable practice, but the public pressure has been too great, and to-day the