M. Sprengel's opinion that many more might be discovered by carefully conducted chemical analyses. 2095. The value of these animal excrements as manure depends very much upon the age of the animals, their kind, their mode of employment, the kind and quantity of food they eat, and the nature of the water they drink. Thus :-Age has effect; for the excrements of a full-grown animal are much better than those of young animals. The state of the animal has an effect; the manure from oxen being much better than that from cows, a great proportion of the substance of whose food goes to the production of milk; and in like manner the manure of the wether is better than that of the ewe. The state of the food has an effect; for sheep chewing their food more minutely than cattle, their manure is richer than that of cattle; and the manure derived from cattle fed on the food in the natural state, is better than that derived from food which has been boiled or scalded; but the manure from scalded food is more active than the other, because it is more prepared. The kind of food has an effect; for poor and scanty food cannot supply so rich manure as nourishing and abundant food. The way in which Water in 100,000 parts by weight,. Urea, along with some resinous colouring matter, the animals are treated has an effect; for working cattle afford better manure than fattening oxen, because the latter abstract from the food, to support their increasing flesh and fat, the same materials as go to produce milk in cows. The water drunk has an effect; for an ox that drinks 80 lbs. of water a-day will pass more urine than a cow which drinks the same quantity, because a large proportion of the water she drinks goes to the formation of milk. Boussingault found that a cow which drank 132 lbs. of water a-day passed 18 lbs. of urine, and gave 19 lbs. of milk; an ox that drank the same quantity gave 40 lbs. of urine. A horse that drinks 35 lbs. a-day passes only 3 lbs. of urine-no more than a man. This latter fact seems remarkable; but when we consider the much greater extent of surface over the body of a horse compared to that of a man, the insensible perspiration of the horse must carry off a large proportion of the liquid food; whereas a man drinks daily only one-tenth more than the urine he passes. 2096. A comparison of the composition of cows' urine fresh, and after it has been kept a month, will show the change that takes place in it by exposure to the air: Cows' urine. Fresh. A month old. 95,442 487) occurring partly in an uncom bined state. 92,624 4,000 1,000 10 Mucus, 664 554 Sulphuric acid, Phosphoric acid, combined with soda, lime, and Chlorine, magnesia, forming salts, month, it contains more than as much again of ammonia as urine in a fresh state. The ammonia is derived from the decomposition of the urea, and the other organic bodies containing nitrogen. The caustic ammonia remains partly dissolved in the water, and is the substance through which urine not properly putrefied is so apt to injure plants. If exposed long to the atmosphere, the caustic ammonia absorbs from it carbonic acid, becomes mild, and the urine may then be employed without danger as a manure for vegetation. But, on urine being thus exposed to the air, part of it escapes in the form of gas, so that it is proper to add to putrefying urine some acid principle to neutralise the ammoniato fix it, as it is usually termed; and this is most simply and perhaps economically done by adding water to it, which, of equal bulk to the urine, enables the diluted mass to retain four times as much ammonia; that is, in every 100,000 lbs. of diluted urine, 1135 lbs. more of ammonia is retained. Another simple substance for fixing the ammonia is black vegetable mould, which supplies humic acid, and every 90 lbs. of it saturates 10 lbs. of ammonia; but as the best earth contains only 45 per cent of humic acid, 200 lbs. of earth will be required to fix every 10 lbs. of ammonia. Chemical ingredients may be employed to fix the ammonia, but they are all costly. 2098. It is rather important to trace the change in liquid manure occasioned by keeping. Fresh urine of cattle has a yellow colour, occasioned by a small quantity of resinous colouring matter; but on standing exposed to the air, the yellow assumes a brown, and at length a black colour, attributable to the formation of humic acid. In winter, urine does not possess a trace of ammonia, whereas it does in summer, thereby indicating the decomposition of urea by heat in the body before the emission of the urine. The above table shows that exposure of urine for a month to the air has the same effect of decomposing the urea as heat has in the body; and four weeks are not sufficient time to decompose all the urea, as still 0.600 remains. When exposed for three months and longer, urine loses its carbonate of ammonia, which is evaporable as well as the crude ammonia itself. In short, a six months' urine contains not a trace of its original urea, mucus, and albumen, and new acid combinations take place, such as the lactate, humate, sulphate, acetate of ammonia. Urine is supposed to be in a ripe state after it has putrefied in summer for five or six weeks, and in winter for eight or nine, though no absolute rule can be laid down for this point, so much depending on the evaporation of the air. The chemical rule for knowing the ripeness of urine is when it contains neither urea nor caustic ammonia, and this can only be ascertained by chemical investigation. After exposure to the air a year and half, urine contains no organic remains, and only salts and mineral bodies dissolved in water. * Thomson's Animal Chemistry, p. 493. 2103. If urine is applied to grass land or to growing crops, while the urea is undecomposed, or the ammonia is in a caustic state, it will destroy vegetation; but it may safely be applied to the ploughed soil at any time, in as far as the soil is concerned, although it is better received by the soil in some states than in others. Winter is considered the best season for applying the liquid manure, not only because it is then most abundant, but the ground, being all ploughed, is then also in the best state for imbibing it: and if applied to the soil just as it has flowed into the tank, much trouble will afterwards be saved in driving out the water, which must be put amongst it to save the ammonia, and which, in fact, is better saved by the humus of the soil. Evaporation, too, in winter is very limited; and any rain that falls will only serve, by dilution, to retain the ammonia, should it attempt to escape. Frozen ground will not take in liquid manure, though it may be safely emptied upon snow. Very dry ground will not take it in easily. If desired to it 2105. Hence," as M. Sprengel properly concludes from such premises, will be obvious to every one that the urine tanks are no such excellent arrangements as they are frequently represented to be; and that it is, in many cases, more profitable to pour the urine over the dung in the dung-pit, or to supply as much straw that the whole of the urine may be absorbed, for then the humic acid arising from the solid excrements will be combined with the ammonia formed, at the same time, from the urea, &c. There is this additional advantage, that the urine, as the most efficient portion of animal excrement, being mixed with the dung, may be distributed more equally over the ground, that no manure-barrels, &c., are required, and that there is no necessity to bestow labour on the preparation of the urine; for the urine, if any, which is not taken up by the dung, may always be most profitably employed in the preparation of compost. In some parts of central Germany, they pour the urine, time after time, into conical heaps of common earth, hollowed to a proper depth in the middle; and when these have stood the proper length of time, and been thoroughly worked for use, they are led to the field. This process is very advantageous where good mould, or earth rich in humus, is not to be had, but must be conducted with the requisite caution: we must, for instance, not pour into the heaps so much urine, that the liquid penetrates through them and escapes; for, even when perfectly clear and colourless, it always still contains carbonate of ammonia, and other ammoniacal * Johnston's Lectures on Agricultural Chemistry, 2d edition, p. 811. 2106. Good as the practice is of saturating rich mould with urine, it is not so advantageous as might be supposed. I formed a cess-pool which received the entire drainage from the house, including that from the water-closets and scullery, amongst a quantity of the richest mould I could collect, and on every year putting the compound or compost on the soil, it was not to be compared in its effects to those of common farm-yard dung or bonedust. It is doubtless to the mixture of the contents of privies, along with the solution of large quantities of rape-cake in the urine, that the liquid manure used in Flanders owes so much of its efficacy. The same composition in this country would be by far too costly an application, though, of course, equally efficacious. Flanders they call this compound bonbons, (sweet-meats,) to show their high estimation of it. manure. ON SEA-WEED AS MANURE. In 2107. Winter is the season which supplies the greatest quantity of sea-weed for After a severe storm, or even a heavy ground-swell of the sea, large quantities of this remarkable substance are cast ashore in the bays and estuaries of the coast; and so desirable is it as a readymade manure for the land, that on those farms which border the sea-coast of our island, and in localities accessible to the shore, the farmer defers every other work in which he may be engaged, to secure a manure which cannot be purchased elsewhere. So well aware is he that the next rising tide may sweep away what the former one had deposited, that his chief aim at the time is to draw the weed beyond the reach of the approaching waves, and then at leisure to drive it upon the particular fields which are destined to receive it. 2108. In East Lothian, on whose shores large quantities of sea-ware are thrown every year, it is put on the land to the amount of 32 loads per acre; and it being preferable to concentrate its beneficial effects on a limited number of acres, than to attenuate its power over a larger space, as much per acre as desired is put on at once, and the extent of ground manured is measured by the quantity supplied by the sea. The quantity thus supplied depends entirely on the nature of the season, as also on the occurrence of storms at the particular period when the plants are most easily dissevered from the rock. It is this uncertainty of the supply which throws a doubt on the statement of Mr Kerr, in his agricultural report of Berwickshire, that the rents of those farms in East Lothian which have access to seaweed, are enhanced to the extent of 25s. to 30s. per acre;† and whatever may have been the case in his day, so great an influence on the value of land is not produced now by sea-weed. 2109. Sea-weed is put on in a fresh state upon the stubbled land before it is ploughed, in winter, in preparation to manuring the soil for the ensuing potato or turnip crop. It is also spread upon the lea ground in'tended to be ploughed for oats. The weed does not soon become desiccated in winter; and though rain fall, it only dissolves the mucilaginous and saline substances easily separable from it, and carries them into the soil; and these two classes of ingredients, no doubt, render the weed so good a top-dressing on every state of the soil. It is only on land capable of bearing green crops that sea-weed can with propriety be applied in winter, for heavy land would then be poached by the horses and carts; and I think it must be this circumstance, more than any other, which gave rise to the opinion that sea-weed does more good to light than to heavy land. 2110. Sea-weed is also used in a fresh state in winter in trenched ground. In some parts of the coast which is composed of sand, and upon which sea-weed is cast, the inhabitants use the weed by placing it in the bottom of every trench two feet deep, nearly filling them with it, and tramping it in, and then throwing the soil upon it, there to remain until spring, when the surface of the ground is prepared for the sowing of carrots. * Journal of the Agricultural Society of England, vol. i. 455-80. 2111. Sea-weed is very succulent, feels slimy, and, when exposed to the summer sun, soon dries into one-third of its bulk, and becomes hard and brittle. 2112. It has been recommended to dry sea-weed, to its being easily carried into the interior of the country; but this would be troublesome in winter; and it is unnecessary trouble, inasmuch as there is no more sea-weed cast ashore than what can easily be used upon the farms on the coast. 2113. Sea-weeds constitute a numerous family of plants. Lindley, in his natural system, places them in class i., Thallogens, alliance 1, Algals; order 3, Fucaceae, sub-orders 2 and 3, Halysereæ, Fuce. In the Jussien system, they are placed under class i., Acotyledones, order Alga. Professor Lindley observes of this tribe of plants, "like all this alliance, the sea-wracks have no particular geographical limits, but occur whereever the ocean or rivers spread themselves over the land. They are, however, remarkable for the enormous space which single species of them occasionally occupy; some of them forming subaqueous forests in the ocean, emulating in their gigantic dimensions the boundless element that enfolds them. Scytosiphon filum, a species common in the North Sea, is frequently found of the length of 30 or 40 feet; in Scalpa Bay, in Orkney, according to Dr Neill, this species forms meadows, through which a pinnace with difficulty forces its way. Lessonia fuscusens is described by Borry de St Vincent as 25 or 30 feet in length, with a trunk often as thick as a man's thigh. But all these, and indeed every other vegetable production, is exceeded in size by the prodigious fronds of Macrocystis pyrffera. This appears to be the sea-weed reported by navigators to be from 500 to 1500 feet in length; the leaves are long and narrow, and at the base of each is placed a vescicle filled with air, without which it would be impossible for the plant to support its enormous length in the water, the stem not being thicker than the finger, and the upper branches as slender as common pack-thread. Some of the species are eatable, owing, doubtless, to the large quantity of gelatinous matter that they secrete. The young stalks of Laminaria digitata, and saccharina, are eaten under the name of 'tangle.' When stripped of the thin part, the beautiful Alaria esculenta forms a part of the simple fare of the poorer classes of Ireland, Scotland, Iceland, Denmark, and the Faroe Islands. In some of the Scottish islands, horses, cattle, and sheep, feed chiefly on Fucus vesciculosus during the winter months; and in Gothland it is commonly given to pigs. Fucus serratus also, and Scytosiphon filum constitute a part of the fodder upon which cattle are supported in Norway."* 2114. Four species are very common on our coast-the Laminaria saccharina, consisting of a single linear elliptic leaf, without any mid-rib; the Laminaria digitata, or common tangle, a cylindrical stem, sometimes as thick as a walkingstick, and about two feet long: the Fucus vesciculosus, consisting of a double stem, with the edges of the leaf entire, and in the disc of which, near the edges, are immersed a number of vescicles or air-bladders-or crackers, as they are vulgarly called, because they emit a loud report on being ruptured by pressure-about the size of a hazelnut, and the use of which, no doubt, is to float the leaves in the water: and the Halidrys siliquaria, consisting of a waved coriaceous stalk about 4 feet long, greatly branched, dark olive when fresh, and quite black when dry; and it is also furnished with air-bladders or vescicles. 2115. The constitution of these plants is very complicated, affording no fewer than 21 ingredients. The first species, Laminaria saccharina, afforded the following substances to the analysis of Gaultier de Claubry in 1815: A saccharine matter-manna. Subphosphate of lime. Subphosphate of magnesia. Oxide of iron, probably united with phosphoric acid. Oxalate of lime. The composition of the other species, together with the Fucus serratus-which is like the F. vesciculosus, but without air-bladders-and the Scytosiphon filum, or thread tangle, is very similar to the one here given.+ 2116. On combustion, in a particular way, seaweed yields an impure salt named kelp. So long as it is used in the arts, kelp is too expensive to use as a manure. It supplied at one time the soda used by the bleachers, but, at the introduction of foreign barilla, its use as such was discontinued, much to the loss of many proprietors and labourers in Scotland; but the barilla itself has been superseded since the very low price at which soda ash, the dry crude carbonate from the decomposition of sea-salt, is now sold. Kelp, however, is now manufactured into iodine. 2117. The composition of the ash of sea-weed *Lindley's Vegetable Kingdom, p. 21. + Thomson's Organic Chemistry-Vegetables, p. 944-6. Transactions of the Highland and Agricultural Society for March 1847, p. 629; and for October 1847, p. 75. |