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great advantages from tho addition of bone-ashes, in variousproportions, according to the nature of the work for whichthe composition is intended.

This author describes an invention of his own for a supe-rior kind of mortar, or stucco, applicable to ornamental workin imitation of stone. As the same general principles oughtto be followed in making even the commonest kinds of mor-tar, we shall insert here the instructions given by Dr.Higgins.

Of sand, the following kinds are to be preferred ; firstdrift-sand, or pit-sand, which consists chiefly of hard quar-tose flat-faced grains, with sharp angles; secondly, thatwhich is the freest, or may be most easily freed by washing,from clay, salts, and calcareous, gypseous, or other grainsless hard and durable than quartz; thirdly, that which con-tains the smallest quantity of pyrites, or heavy metallicmatter, inseparable by washing ; and fourthly, that whichsuffers the smallest diminution of its bulk in washing.Where a coarse and fine sand of this kind, and correspond-ing in the size of their grains with the coarse and fine sandshereafter described, cannot be easily procured, let such sandof the foregoing quality be chosen, as may be sorted andcleansed in the following manner :—

Let the sand be sifted in streaming, clear water, througha sieve which shall give passage to all such grains as do notexceed one-sixteenth of an inch in diameter ; and let thestream of water, and the sifting, be regulated so that all thesand which is much finer- than the Lynn-sand, commonlyused in the London glass-houses, together with clay, andevery matter specifically lighter than sand, may be washedaway with the stream; whilst the purer and coarser sand,which passes through the sieve, subsides in a convenientreceptacle, and the coarse rubbish and rubble remain on thesieve to be rejected.

Let the sand which thus subsides in the receptacle, bewashed in clean streaming water through a fine sieve, so asto be further cleansed, and sorted into two parcels ; a coarser,which will remain in the sieve which is to give passage tosuch grains of sand only, as are less than one-thirtieth of aninch in diameter, and which is to be saved apart under thename of coarse sand, and a finer, which will pass throughthe sieve, and subside in the water, and which is to be savedapart under the name of fine sand. Let the coarse and thefine sand be dried separately, either in the sun, or on a cleaniron-plate, set on a convenient surface, in the manner of a\ sand-heat.

j j Let the stone lime be chosen, which heats the most in! slaking, and slakes the quickest when duly watered ; thatwhich is the freshest made and closest kept ; that whichdissolves in distilled vinegar with the least effervescence,i and leaves the smallest residue insoluble, and in the residuethe smallest quantity of clay, gypsum, or material matter.Let the lime, chosen according to these rules, be put in abrass wired sieve, to the quantity of fourteen pounds. Letthe sieve be finer than either of the foregoing ; the finer thej better it will be: let the lime be slaked, by plunging it into a buttj filled with soft water, and raising it out quickly, and sufferingj it to heat and fume; and by repeating this plunging andraising alternately, and agitating the lime until it be made[ to pass through the sieve into the water ; and let the part ofI the lime which does not easily pass through the sieve berejected: and let fresh portions of* the lime be thus used,until as many ounces of lime have passed through the sieve asthere are quarts of water in the butt,j i Let the water thus impregnated stand in the butt, closelyI i covered, until it becomes clear ; and through wooden cocks,j placed at different heights in the butt, let the clear liquor be

drawn off, as fast and as low as the lime subsides, ^° l ^This clear liquor is called lime-water. The freer theis from saline matter, the better will be the cementing Mmade with it. . ,. e <|,

Let fifty-six pounds of the aforesaid chosen lime be sby gradually sprinkling the lime-water on it, and es P'on the unslaked pieces, in a close clean place. Let the s' ^part be immediately sifted through the last-mentionebrass-wire sieve : let the lime which passes be used inst£l jinieor kept in air-tight vessels ; and let the part of thf p C rwhich does not pass through the sieve be rejected. T" l 3 - e fe,and richer part of the lime which passes through ^'? 3 ,tli 9may be called purified-lime. Let bone-ash be prepared >' j e | jusual manner, by grinding the whitest burnt bones; bit be sifted, so as to be much finer than the bone-as ' 1monly sold for making cupels. .

The best materials for making the cement being rt y.prepared, take fifty-six pounds of the coarse sand, and c ftwo pounds of the fine sand ; mix them on a Ur ° e f L th»*hard wood placed horizontally, then spread the sand s ° r ^ lC eit may stand to the height of six inches with a flat s gge ron the plank, wet it with the lime-water, and let any ^011fluous quantity of the liquor, which the sand in the c<J® ( |,0

described cannot retain, flow away off the plank.wetted sand add fourteen pounds of the purified j 1 ’ a p

if

then 1era 1

several successive portions; mixing and beatingtogether, in the mean time, with the instruments g e " uused in making fine mortar; then add fourteen P°^ a ti^

the bone-ash,all together.

in successive portions, mixing

and

The quicker and more perfectly these materials areand beaten together, and the sooner the cement thus ^o sS ‘is used, the better it will be. This may be called.grained cement, which is to be applied in buiIdi ! ,g „’, 1 d 0 W ct ;!plastering, stuccoing, or other work, as mortar andgenerally are; with this difference chiefly, that, as th ' 9 c jehis shorter than mortar, or common stucco, and dries ^ ii>it ought to be worked expeditiously in all cases ; , 8l dsstuccoing, it ought to be laid on by sliding the trowel j'P^ilil'on it. The materials used along with this cement lD 0 \ni>ing, or the ground on which it is to be laid in stU j I 1 .t:a 1 jought to be well wetted with the lime-water in the ' uS e<Jof layihg on the cement. The lime-water is also towhen it is necessary to moisten the cement, or when ais required to facilitate the floating of the cement.

i **

When such cement is required to be of a still fine'

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take 98 pounds of the fine sand, wet it with the li*n e tb * 5and mix it with the purified lime and the bone-as'b^ t |ii ' 9quantities and in the manner above described, "* (3 , a 1 ’ 6difference only, that 15 pounds of lime, or thereabo .. t |,eto be used instead of 14 pounds, if the greater p nl , fail'

tan , llt .

Lynn sand. This may be call® ^ t h®It is used in giving the last coating' .,jii® 1 '

l*' V .a 0*

sand be as fine asgrained cement.

finish, to any work intended to imitate the fine*' uS ,stones or stucco. But it may be applied to all thethe course-grained cement, and in the same manner, .^jngi

it * 91

t/ , -— --—

When, for any of the foregoing purposes 01 j c o:i r51 ,

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building, &c., a cement is required much cheapergrained than either of the foregoing, then much coaI ^ e d fi 11 "sand than the foregoing coarse sand, or well was r jl>'rubble, is to be provided. Of this coarse sand, ^ 2^ble, take 56 'pounds ; of the foregoing coarse 9pounds; and of the fine sand, 14 pounds ; and, aft er _ j,, tl ,ethese, and wetting them with the cementing Hfl 110 ’’ g ( tl>®foregoing manner, add 14 pounds, or somewhat '

bone-ash, mixing them together in the manner vV Jiitdescribed. When the cement is required to be wh* ’