4. Empyreumatic oil.

5. Rich ammoniacal liquors.

In order to economise the lime employed in the purification of gas, it is proposed to employ a purifying powder, composed onehalf of any of the natural or artificial sulphates of lime (by preference, plaster which has been used in building), animal charcoal, vegetable charcoal, coke, river or sea saud, spent bark, sawdust, peat or turf, sulphate, and oxide of lead, all reduced to powder, and wetted with dilute sulphuric acid, or acidulated water of 6° to 7° Beaumé. The gas to be purified is made to pass through perforated metal plates, or wire gauze shelves, upon which is laid moss to prevent the apertures being clogged by the refining powder which is laid thereon. The lime is laid above the powder. The quantity of lime employed is one-third, and that of the refining powder two-thirds; which last is composed of purifying substances, such as the sulphates of lime, inert sub. stances rendered purifying, such as sawdust, saturated with sulphuric acid; and inert substances, such as powdered coke. When the materials are charged with too much ammonia or sulphuretted hydrogen (which can be ascertained by causing the gas to come in contact with turmeric test-paper, and paper saturated with acetate of lead, which will be turned black), they are to be replaced by a fresh supply of refining powder and lime.

No claims are made in this specification.

Improvements in making Roads and Ways, and in Covering the Floors of Courtways, Buildings, and other similar purposes. A communication. A. ROHN, Paris. Sealed Aug. 1, 1849.

The object of M. Roehn's invention is the employment of natural or artificial asphalte in a cold state; and it is proposed to be conducted by either of the following methods, according to the resources and character of the locality where the paving or covered way is to be laid down :

Or when the asphaltic rock cannot be procured, the mastic may be prepared with

Common gray or hydraulic
lime.....
Refined coal tar
Pyrogeneous oil

lbs.

220

170 7

The pitch is first melted, and the asphalte or lime added, after which the oil is poured in, and the whole is made to simmer gently until the ingredients are thoroughly incorporated. It is then cast into slabs, which, when cold, are employed for paving, in the ordinary manner, sand being added in the proportion of about 60 per cent.

II. The road is levelled, and a stratum of wet gravel, about two inches deep, is rammed down smooth over it. A layer, about four inches deep, of macadamised stones is laid upon the gravel, and then, above the stones, a second layer of asphaltic rock, broken into pieces of two inches, one inch and a half, and half an inch in size, which have been placed in an open basket, and dipped in pitch. The road is next beaten, or rolled level, to cause the pieces of asphaltic rock to bind together, and the interstices between them are filled up with an elastic mastic, which is ladled on to the road, and scraped over it, which is well understood by asphaltum layers of the present day. Being of a yielding nature, this sort of paving affords firm footing to cattle travelling upon it. The elastic mastic is composed of―

for use.

IV. When parts of the road are worn away, they are to be brushed over with a mixture of Bastenne pitch and pyrogeneous oil, and gravel sifted over them.

The pyrogeneous oil is employed to toughen the material, and a road constructed as above described will, it is said, be ready for traffic in forty-eight hours after it is completed.

Claims-1. The preparation of a hard and durable mastic, by the employment of bitumen, pitch, fixed oils, and calcareous substances.

2. The mode of preparing the elastic mastic.

3. The preparation of artificial asphaltic

rock.

4. The preparation and use, in a cold state, of mastic, or natural or artificial asphaltic rock, in combination with stones or other hard substances, to form a covering for a road.

5. The mode and use of mastic in the form of sand.

6. The preparation of asphaltic rock in such a manner that, without heat, it shall be rendered soft and binding by beating or rolling, whereby a double asphaltic covering to the road is formed.

Improvements in the Application and Combination of Mineral and Vegetable Products; also, in obtaining Products from Mineral and Vegetable Substances, and in the Generation and Application of Heat. JOHN KNOWLYS. Aug. 9, 1849. The improvements described in this specification relate chiefly to paints or pigments.

I. The patentee's first product is obtained by reducing silicate of manganese to powder, then grinding it up with oil. The result is a pigment of a light brown color, which may be employed alone, or mixed with peroxide of iron, oxide of zinc, or other coloring materials, to give them tone and body. Or, instead of the silicate of manganese, corun

dum, greystone, limestone, feldspar, blue clay, Kimeridge coal, jet, anthracite, any of the varieties of pyrites of iron, iron ores, the residuum of copper, antimony, and arsenical ores reduced to a friable state, and similar mineral substances may be employed. The grinding surfaces are made hollow and kept cold by the passage of cold water through them, and have a motion communicated to them similar to that employed in grinding glass.

II. To purify the crude oxides of zinc, which contain sulphur and other impurities, they are to be dissolved in sulphuric acid, and the solution allowed to stand until the impurities have subsided, when the clear liquor is decanted off, and a solution of carbonate of soda added to precipitate the zinc, which is dried and reconverted into oxide of zinc, when it is ready to be used as a paint or pigment. The sulphate solution is converted into the carbonate solution, and rendered again applicable. Hydrochloric, or acetic acid, may be used instead of sulphuric acid. Or, instead of the preceding process, the crude oxide may be ground up with lime or carbonate of lime, or carbonate of lime and magnesia combined.

III. It is proposed to employ the carbonaceous residuum from the manufacture of prussiates of soda and potash as a pigment, also as a manure and deodorant. To render the residuum fit to be employed as a pigment, it is to be washed and ground up with oil, or muriatic acid is added to the residuum for the purpose of combining with the oxide of iron which it contains, and forming a salt of iron. It is then washed in water to carry off the saline and other impurities, and is ready for use. The resulting product is termed by the patentee "horn black," and may be employed as a black pigment, alone, or mixed with any of the substances before enumerated. The residuum may be used as a manure, either as first obtained, or when deprived of its iron; it may also be applied in its natural state to the deodorising of noxious matters.

IV. To clarify and bleach linseed oil, &c., it is proposed to cause it to flow, in finely divided streams, down a tower with glazed sides, and to encounter a current of air forced up in a contrary direction, so that it may be subjected to the action of light and air. The same apparatus, with the addition of steam pipes, may be applied to the evaporation and concentration of syrups and saccharine solutions. Or, instead of steam, cold water may be caused to flow through the pipes, and the apparatus then applied to cooling heated liquids.

V. The last improvement refers to certain

steam-boiler furnaces, which were the subject of a former patent granted to Mr. Knowlys, and consists in causing the flues of two furnaces placed on either side of the boiler to descend, and then turn up and open into a tube, placed concentrically, and within the boiler, which leads to the chimney. Claims-1. The mode of grinding colors above described.

2. The application of the various substances enumerated under the first head of the specification, either alone or combined with ordinary coloring materials, as paints or pigments.

3. The mode of purifying the crude oxides of zinc by the process above described.

4. The employment, with the crude oxides of zinc, of lime, carbonate of lime, or carbonates of lime and magnesia, combined, for the purpose of rendering them fit for being used with paints or pigments.

5. The application of the carbonaceous

residuum obtained in the manufacture of the prussiates of potash and soda, when treated as described, either alone or combined with other materials, as a paint or pigment.

6. The application of the said residuum, either when in its natural state, or when deprived of its iron, as a manure.

7. The application of this residuum, in its natural state, to the deodorising of noxious matters.

8. The employment of the apparatus for clarifying and bleaching linseed and other oils and fats, for evaporating and concentrating syrups and saccharine solutions, and for cooling liquids.

9. The use and application of a pyrometer attached to the subliming vessel.-[A cover is placed on the vessel, so as to leave an air space between the two, to prevent too great a radiation of heat; and the heat of the exterior of the vessel will be indicated by a pyrometer on a dial in the usual way.]

SANITARY NOTES.

NO. VI.

MUCH diversity of opinion has been expressed with respect to the propriety of permitting or forbidding a practice, which has obtained to a great extent in all crowded towns, viz., building houses in courts and narrow streets, back to back. The reason given for not forbidding the practice is that houses may be ventilated without having a space at the back, and that such a regulation would act as a private injury, the interests of the landlord being affected by the number of houses that can be put on the ground. Now here is a point in which that golden maxim" Property has its duties as well its rights," is most applicable. Property has certainly the right to possess as large a material value as possible, but it has no right to swell that amount in its private ledger, by abstracting from the public ledger of health even one iota of spiritual valueits paramount duty is the social one of contributing to the public weal; and this is inconsistent with the construction of dens of filth, disease, and infamy.

That houses for the poor who congregate generally in large numbers, can be constructed back to back with proper attention to sanitary requirements, must be broadly denied. To construct privies in front, in the public way, is an outrage to public decency; to construct water-closets in houses, which are the resort of the poorest, would simply be a waste of money and a creation of a positive evil in the house. Next to the indiscriminate herding together of the sexes at night in the same room, as in the common lodging houses, there is not a more active provocative of public immorality than the public situations and scanty numbers of these necessary accommodations: their construction ought to be regulated so as to secure both privacy and freedom from effluvium in the houses. Again, no competent plan has yet been proposed for ventilating the rooms of back to back, and, therefore, the poorest houses. All kinds of apertures, whether covered with perforated plates or not, will, invariably, in a short time, be covered up in some way. The proposition of air flues, for inducting fresh air and educting the vitiated air, is a hopeless one for houses where there are often no fires to set the

currents in motion, and prevent the flues becoming, like sewers, the depositories of decomposed air and noxious gases. In houses of this kind, where there are small fires, every channel will be speedily stopped which can increase the consumption of fuel. No plan will ever succeed that depends (as some professedly do) on the want of penetration of the poor. The main requirement must be to give plenty of air around the house. The importance of a full circulation of water has been already insisted on in these notes, but a full and free circulation of air is fully as necessary. So great, indeed, is the evil of stagnant air, that in some deep gorges in high mountain lands, the scanty inhabitants are almost constantly afflicted with scrofula and consumption, owing to the noncirculation of the air; as from the prevalent direction of the wind, in relation to the peculiar position of the gorges, it seldom blows into them, and the air is therefore seldom changed.

Sufficient has been said on this part of the subject to justify the conclusion that the Legislature ought to provide that all courts should be open at both ends; that they and the low-class streets should have a width in some degree proportionate to the height of the houses on each side, and such width should never be less than twelve feet; that the back space between rows of houses should be of equal width to the front space; and that there should be proper private accommodation for the corporal necessities of the inhabitants.

The

There are two points in the construction of houses which it is possible to regulate; viz., the height of the rooms, and the quantity of window space. Known instances of the habitual crowding of human beings into confined spaces are so numerous and wellestablished, that it is impossible for any one to ignore all knowledge of the facts. foal stench of the steaming cauldrons, which many of the public lodging rooms really are, has been feelingly described by the fre. quenters of such places; the bodily oppression, sickness, and headache which follow a few hours spent in such rooms are but a natural consequence, and one directly leading to a high rate of mortality. The same remarks apply to those houses inhabited by artisans, where manufactures are carried on by day, and the family sleep by night in the

same room. Now, the evils here alluded to are at least capable of mitigation by legislative enactment. Each grown person inhales about 300 cubic feet of air in the course of the night. If, therefore, six persons are sleeping in an apartment 12 feet square and 7 feet high, they have little more than half the quantity of fresh air to breathe that they require, and of course the remaining half is made up by the vitiated air they have exhaled, and which is no longer fit for use; but if it were obligatory that a room 12 feet square should be 9 feet in height, those 6 persons would have each 264 cubic feet of fresh air out of the required 300, and would, therefore, inhale during the night only 36 cubic feet of vitiated air. It will always be difficult, if not impossible, to regulate the number of persons that shall be admitted into private apartments; but there is no difficulty in securing to them a reasonable amount of air to breathe, by regulating the height of rooms according their areas.

With respect to window space, all that is asked at present is, to "leave it alone." The window-tax is, emphatically, a tax for the promotion of public ill health, and the encouragement of filth and vice. The rigid. ness with which it is enforced, too, is almost marvellous. It not long ago happened that an architect, in his desire to secure a good ventilation for some parts of a building, contrived to bring his air channels under the door-steps, and there in nearly absolute darkress, he made an opening in the wall. That opening was taxed as a window, and was, therefore, necessarily closed. There will be no use in providing back spaces for low class houses, unless there can be windows in the back wall; and there will be neither staircase nor other supernumerary windows there, as long as this tax exists. Great is the anxiety, and careful are the calculations of a builder of third and fourth rate houses, to build as much house with as little window as possible, so as to avoid the grasp of the infamous window tax. It is vile hypocrisy to attempt to improve the health and morals of the poor, without making reference or allusion to this prime promoter of all that is bad in both, the connection of darkness and vice is of ancient date, and is marked in lofty words" They love darkness rather than light, for their deeds are evil."

In the model lodging-house in Spitalfields, an excellent ventilation has been contrived, so that in the large coffee-room, even when filled, the air is quite pleasant. But this has been effected by the adoption of an extensive arrangement of flues, fires, and a shaft 100 feet high-means quite inapplicable to ordinary houses, though, doubtless, well arranged

for a public building. At the Now Fever Hospital at Islington, an ingenious and simple plan has been provided for the escape of the vitiated air. It is founded on the principle exhibited in the following experiment Hold a straight piece of tobaccopipe, or similar tube, near a piece of thin card; put the pipe in your mouth and blow hard through it. The card will remain suspended in close proximity to the pipe. The air, meeting at first the resistance of the paper, escapes in a curved form in every direction, and any dislocation of the card would produce a vacuum in the point of separation of the curves, which is, of course, immediately opposite the line of forcible expulsion. The pressure of air on the back of the card at that point keeps it, therefore, in place. This has been applied as follows: a narrow slit is made across the ceiling of the wards at the space between each of the joists; these slits communicate with longitudinal airways through the joists, which are brought over the centre of the wards to a vertical shaft passing out through the roof. Over the shaft is placed a rectangular head, extending a little on each side of the shaft, of such a form and size that the areas of both ends of the head are about equal to the area of the shaft. Thus the wind blowing in at one side of the head cannot pass down the shaft, for then it must draw in from the other end, and a vacuum would take place at the junction of the curved currents; but it must blow through the head, and thus give an upward motion to the air in the shaft.

It is very much to be desired that, in private houses, more attention were paid to a proper ventilation of the rooms, which are often "crowded to suffocation" by visitors and parties. A return to the elegant practice of ornamenting ceilings would give ample opportunity for screening the apertures of escape, which ought to be either numerous or connected with the warm air of the chimney. It is a great mistake to suppose that one or two simple outlets in a ceiling are sufficient, for in that case instead of their being space for the bad air to escape, there is merely a provision for the falling down of the heavier body, viz., the cold air, and, consequently, the more thorough remixture of the vitiated air in the atmosphere of the room. When proper means are provided for the escape of the bad air, good air will almost always find its way in; but a more scientific plan is, to provide for its admission, which may be done by means of flues introducing the air into the neighborhood of the fire, and then distributing it round the skirting of the

room.

In the great majority of shops, workshops,