Divided interests exert another reactive influence. The public authorities are debarred from making full avail of the latest improvement in the art and craft of waste recovery. For instance, although the leading abattoirs of these islands have acquired reasonably up-to-date plants, they are all operated upon the open steam principle, with and without vacuum. The method, while satisfactory so far as it goes, does not offer the means of securing the utmost from the available material. But the authorities do not feel justified in going to the expense of acquiring the latest appliances for the prosecution of the work of reclamation, an attitude which is perfectly explicable in the circumstances.

Of course, the community suffers, though imperceptibly. The plants in question allow a certain proportion of waste to be lost which in the course of the year represents an imposing figure. Furthermore, the whole, or the greater part, of the “stick liquor” or gelatinous liquid thrown off during the fat reclamation process is lost, being allowed to escape down the drains. The abandonment of the stick liquor is regrettable because it constitutes a waste capable of being treated with profit, as I explain later. But it is doubtful whether the average municipal plant, even if it had absolutely unfettered control of all the waste products arising from the slaughter of cattle for food, would be in the position to treat the stick liquor to commercial advantage. An evaporative plant would have to be incorporated to concentrate the gelatinous substance to the desired density, and only in a few instances would the quantity of material treated be adequate to render the utilization of the stick liquor profitable. But this constitutes an additional argument for centralized meat packing and offal exploitation in these islands.

Accordingly effort is exclusively confined to the recovery of the grease. I have described the outstanding features of the vacuum system in a previous chapter, to which I would refer the reader desiring enlightenment in connection therewith. The grease is drawn off by a special skimming device into a fat tank to be clarified. Then it is run into barrels or other suitable receptacles for transport. It is scarcely necessary to point out that the grease and tallow thus obtained from condemned meat and other offal, although thoroughly sterilized in the rendering process, are graded only as fit for the manufacture of soap and other articles of utility, as distinct from products of edible importance.

The term “offal” in its application to meat residues is somewhat ambiguous. It not only comprises material coinciding with the general interpretation of the term, but certain portions of the animal which are really suited to the preparation of foodstuffs for the table. Consequently all grease recovered from the digester is not necessarily adapted to manufacturing purposes only. In these circumstances it is necessary to grade the fat before treatment, the fresh fat, which is quite suitable for yielding material adapted to the preparation of margarine, for instance, being kept distinct from the lower grades which cannot possibly be classed as edible. Selection and separation treatment of the two grades—edible and inedible—are profitable because, while both are in keen demand, it is the former which is able to command the higher market figure. But when edible fats are sought it is preferable to employ the steam-jacketed digester because the fat thus obtained, from the fact that the steam is not brought into contact with the material during the cooking process, is of enhanced quality, being sweeter, while all the natural properties of the fat are retained for reasons already set forth.

Although, therefore, the most popular system in vogue for reclaiming fat from slaughter-house residues is exposed to criticism, owing to what may be described as lack of efficiency in operation due to the recovery of the fat not being as high as it might be, it appears to meet the conditions of the average municipal abattoir. City and borough corporations, unlike private organizations, are not in the position to scrap an existing plant for one which is of later date and greater efficiency, because there is not the same incentive to reap the utmost benefits attainable as prevails under private conditions where the full brunt of competition is encountered. Of course, the initiative of corporations is just as pronounced as that of private firms and individuals, but it is the exception rather than the rule. Furthermore, the municipality is not in the position to run a plant under full load, or even at a uniform pressure the whole time. It is only able to handle the waste as it accumulates during its own abattoir operations. On the other hand, the private exploiter can acquire a plant of such capacity as to cope with the steady flow of material from the slaughter-houses, thereby keeping the by-product recovery installation working steadily at a point approaching its productive limits.

Nevertheless, the results achieved with the prevailing type of plant afford interesting reading, although it is somewhat misleading to cite them. The material varies so widely both in quantity and quality, while the ultimate fat-yield likewise fluctuates markedly. A fat bullock which has been condemned would naturally be expected to furnish a good contribution of fat. On the other hand, only a low percentage could reasonably be anticipated from a lean cow. In these circumstances a comparison without full details concerning the material handled is difficult. The figures available may be set down as being representative, though they should be accepted as being typical rather than empirical.

A consignment of condemned meat, weighing 2,240 lb., was placed in the digester. The quantities of the respective materials recovered were:—

Lb. Per cent.
Tallow 336or15
Fibrine or meat-meal 392-428or17¹⁄₂-20
Bone-meal 280-336or12¹⁄₂-15

In another instance a somewhat heavier consignment of condemned meat was committed to the recovery plant. Its composition was:—

Lb.
Beef 84,000
Pork 1,607
Mutton 818
Veal 354
Offal 20,370
Total 107,149