Cooley's Cyclopaedia of Practical Receipts Volume I Part 17

of oxygen 20918 to 20966 30 from Berlin gave in 100 parts, by vol. of oxygen 20908 to 20998 10 from Madrid gave in 100 parts, by vol. of oxygen 20916 to 20982 23 from Geneva and Switzerland gave in 100 parts, by vol. of oxygen 20909 to 20993 15 from Toulon and Mediterranean gave in 100 parts, by vol. of oxygen 20912 to 20982 5 from Atlantic Ocean gave in 100 parts, by vol. of oxygen 20918 to 20965 1 from Ecuador gave in 100 parts, by vol. of oxygen 20960 2 from Pichincha gave in 100 parts, by vol. of oxygen 20949 to 20981 ------ ------ Mean of all foregoing 20949 20988 " of the Paris specimens 2096

Vapour of water is essential to the respiration of animals and plants, in order that the organs concerned in this operation may be kept in a soft and moist condition.

Carbonic anhydride is evolved during combustion, putrefaction, and fermentation; it is also a product of the respiration of animals, and highly poisonous to them, even when diluted with large proportions of air.

This gas is, however, greedily absorbed by plants, which decompose it; they a.s.similate the carbon and return the oxygen to the atmosphere, ready to be again consumed in supporting the life of the animal world.

Dr Angus Smith has defined a very pure air to be one that contains with 2099 per cent. of oxygen 030 of carbonic acid (anhydride).

This latter varies in amount in the atmosphere of cities, as will be seen upon inspection of the subjoined table, extracted from Dr Smith's work 'Air and Rain':--

Per cent.

Air of Madrid, outside the walls, mean of 12 a.n.a.lyses, by Luna 045 Mean of 12 a.n.a.lyses, within the walls of Madrid, by Luna 051 Mean of 14 a.n.a.lyses, by Angus Smith, in Manchester suburbs 369 In Manchester streets 403 Usual weather 0403 During fogs 0679

De Saussure's a.n.a.lyses show that there is more carbonic acid on the mountains than in the plains, as might be inferred from the comparative absence of vegetation in elevated positions. Dr Pietra Santa states that the air of hills or mountains, at the height of 2300 feet, is lighter than common air, contains a smaller proportion of oxygen, and is impregnated with a largely increased amount of aqueous vapour. It also contains a large quant.i.ty of ozone. He considers such a climate peculiarly soothing to persons suffering from chest diseases.

Dr Angus Smith's a.n.a.lysis of the air from the mountainous districts of Scotland confirms the above statement of Dr Pietra Santa's. The heaths and mountains of that country are remarkably healthy localities, and the air from them gave on a.n.a.lysis 2094 per cent. by vol. of oxygen, and only 033 of carbonic acid.

Ammonia is derived from the putrefaction of animal and vegetable substances. It is from atmospheric ammoniacal compounds that plants obtain much of the nitrogen which is essential to the formation of many parts of their structure.

Nitric acid, like ammonia, is absorbed, and its nitrogen a.s.similated, by plants.

In addition to the gases and vapours already enumerated, as well as others which exist in minute quant.i.ty, or which are of only occasional occurrence, Pasteur and other investigators have discovered in the air living germs which are capable of exciting putrefaction and fermentation, and which are competent, in some instances, to engender disease when they are injected into the blood of animals. In fact, the spread of infectious diseases, _e.g._, smallpox, typhus fever, cattle plague, &c., is attributed to the presence in the atmosphere of the germs of such maladies. These germs are believed to be living beings, which develope and multiply at the expense of the tissues of the larger animals into whose systems they have found entrance.

=Air, Vitiated.= As has been stated in the previous article, the air consists chiefly of two gases, oxygen and nitrogen. In all open places it has a similar composition, as might be concluded from the constant mingling which takes place by the agency of currents continually in movement, although sometimes to an inconsiderable extent only. Dr Angus Smith regards air as very pure when it contains not less than 2099 per cent. by volume of oxygen, and 0030 of carbonic anhydride (acid).

According as the proportion of the former gas diminishes and that of the latter increases beyond certain limits in the air by which we are surrounded, it becomes more or less deteriorated and unfit to be breathed, particularly as the increased amount of carbonic acid is, in crowded dwellings, a.s.sembly rooms, theatres, and confined inhabited s.p.a.ces, a.s.sociated with deleterious and putrescent exhalations from the person.

_The following tables exhibit the amount of carbonic acid in close places in London._

Per-centage =I.= by volume.

Chancery Court, closed doors, 7 feet from the ground, March 3 193 Same, 3 feet from ground 203 Chancery Court, doors wide open, 4 feet from ground, 1140, March 5 0507 Same, 1240 p.m., 5 feet from ground 045 Strand Theatre, gallery, 10 p.m. 101 Surrey Theatre, boxes, March 7, 1030 p.m. 218 Olympic, 1130 p.m. 0817 Same, 1155 p.m. 1014 Victoria Theatre, boxes, March 24, 10 p.m. 126 Haymarket Theatre, dress circle, March 18, 1130 p.m. 0757 Queen's Ward, St. Thomas's Hospital, 325 p.m. 052 Edward's Ward, St. Thomas's Hospital, 330 p.m. 052 Victoria Theatre, boxes, April 4. 076 Effingham, 1030 p.m., April 9, Whitechapel 126 Pavilion, 1011 p.m., April 9, Whitechapel 152 City of London Theatre, pit, 1115 p.m., April 16 252 Standard Theatre, pit, 11 p.m., April 16 320

Dr Angus Smith states that out of 339 specimens of air obtained from various mines he found 35 normal or nearly so, 81 decidedly impure, and 212 exceedingly bad; he also adds that owing to the frequent firing of charges of gunpowder within the mines, and from other causes, the atmosphere is further contaminated with sulphuretted hydrogen, sulphate, carbonate, sulphide, sulphocyanide of pota.s.sium, and nitrate of pota.s.sium, carbon, sulphur, carbonate of ammonia, organic matter, sand, and sulphurous and a.r.s.enious acids.

The air of large cities, which are the seats of manufacturing industry, is always more or less charged with the exhalations given off by chemical and other works. The sulphuric-acid works contribute sulphuric, sulphurous, nitrous, and a.r.s.enious acids; copper works, in which pyrites is employed, give off large quant.i.ties of sulphurous acid, mixed with a.r.s.enic and a little copper; manure works, in many cases, send out compounds of fluorine, besides sulphuric acid; gla.s.s works, sulphuric and hydrochloric acids; and alkali works, hydrochloric acid (although in small quant.i.ties), which very frequently contains a.r.s.enic. Of ammonia, Angus Smith remarks: "It is one measure of the 'sewage' of the air; it is the result of decomposition. It is not, in these small quant.i.ties, hurtful, so far as we know. The ammonia is in no case free, but combined probably with hydrosulphuric, hydrochloric, and sulphuric acid in towns. In country places it is, at all events partly, united to carbonic acid.

II. _London Air.--Carbonic Acid, Metropolitan Railway, November, 1869._

+--------+----------------------------+------------+---------+---------+ Carbonic Oxygen, Date. Place. Time of Day. Acid, per cent. per cent. +--------+----------------------------+------------+---------+---------+ 1869. Tunnel between Gower Street Nov. 12. and King's Cross Stations; 10 a.m. 150 2060 specimen taken at the open window, first-cla.s.s carriage. " 12. Tunnel between Gower Street and King's Cross Stations; 730 p.m. 078 2079 specimen taken at the open window, first-cla.s.s carriage. " 12. Tunnel Praed Street; specimen taken at the open 1030 a.m. ... 2071 window, first-cla.s.s carriage. " 15. Specimen taken during journey between Gower Street 1015 a.m. 338 2066 and King's Cross, first-cla.s.s carriage, window open. " 15. Same 3 p.m. 155 2070 " 15. Same 11 p.m. 150 2074 +--------+----------------------------+------------+---------+---------+ Average 1452 2070 +--------+----------------------------+------------+---------+---------+ ANGUS SMITH.

_The Air of Mines_ (_Metalliferous_).

+-------------+---------------------+-------+-------+-------+--------+ Name of Mine, Description of place, Thermo- Number Oxygen, Carbonic and depth where taken and time meter, of Men per Acid, from surface, when taken. Fahr. working cent. per in fathoms. in it. cent. +-------------+---------------------+-------+-------+-------+--------+ Hurst End, 300 ft. beyond ... 2 ... 199 a rise, 9 ft. high, 7 ft. wide. Old Gang End of level ... 2 2058 48 " End of level ... 2 ... 28 " (_a_) Rise 7 ft. ... 2 2025 39 high, 132 ft. from current. Gra.s.sington (_b_) End of cross ... 2 2094 06 cut, 480 ft. from rise. " End, 480 ft. from ... 2 1953 159 rise. " Rise 60 ft. high in ... 2 1952 172 shale. " End, 60 ft. from ... 2 2047 106 rise. " (_c_)End, 840 ft. ... 2 2008 94 from rise. +-------------+---------------------+-------+-------+-------+--------+ (_a_) Air machine.

(_b_) Unusual amount of dust.

(_c_) Crystals were chiefly hexagons.

ANGUS SMITH.

The following table, showing the amount of ammonia present in rain collected at the different places named, is from Dr Smith's work, 'Air and Rain.'

COMPARATIVE. AMMONIA.

That of Valentia (Ireland) taken as 1 or 100.

Ireland, Valentia 1 Scotland, sea-coast, country places, west 269 Scotland, inland, country places, west 296 Scotland, sea-coast, country places, average 410 Scotland, sea-coast, country places, east 551 England, inland, country places, east 594 England, sea-coast, country places, west 1055 German specimens 1061 London, 1869 1917 Scotland, towns (Glasgow not included) 2122 St. Helen's 2533 Runcorn 2572 England, towns 2867 Liverpool 2989 Manchester, 1869 3533 Manchester, 1869 and 1870, average 3594 Manchester, 1870 3654 Glasgow 5055

The effects resulting from breathing an impure atmosphere are necessarily dependent upon the extent of the pollution and other conditions. When the contamination is moderate the first effect is headache, accompanied with la.s.situde, and a general paleness of the face and skin, owing to a diminution of the red corpuscles of the blood or to their imperfect aeration; the pulse becomes lowered, and at the same time the breathing is accelerated. When in addition to breathing such air from day to day is superadded the misfortune of an insufficiency of food, scrofula and consumption very often follow. Dr Guy has demonstrated the great mortality that is caused by consumption in those trades in which workmen pursue their calling in hot, close, gas-lit rooms, in comparison with those who pa.s.s most of their time in the open air. The amount of air required by each person in a room is no less than 2100 feet per hour; when the ventilation does not supply this amount of fresh air, the apartment smells stuffy, the furniture becomes coated with a film of organic matter, unless constantly cleaned, and the carbonic acid becomes increased beyond its normal quant.i.ty.

Dr Parkes has shown that bronchitis and consumption are more frequently than not contracted by those who live in an atmosphere of foul air. In the years 1834 to 1847 the proportion of deaths in the ill-ventilated prison of Leopoldstadt in Vienna was 86 per 1000, out of which number 514 per 1000 was due to phthisis or consumption; while in the well-ventilated House of Correction in the same city the deaths were 14 per 1000, of which 79 were from phthisis; hence 435 cases per 1000 of the deaths were clearly traceable to foul air and nothing else.

Mr Noel Hartley, in his valuable little manual, 'Water, Air, and Disinfectants,' says: "During the outbreak of cattle plague in 1866, in sheds containing twenty to thirty cows--which the owners kept closed to such an extent that all c.h.i.n.ks in the doors and windows were stuffed with straw and matting, under an ignorant belief that thus the plague could be kept out--very frequently the entire stock died in two or three days after the first appearance of disease; while in other cases where animals were housed in a well-cleaned and tidily-kept shed, with a plentiful supply of fresh air, not only did some of them escape the disease altogether, but the deaths were reduced to one third of the number of beasts attacked."

The large supply of fresh air necessary in hospitals for contagious diseases is fully recognised by medical men, and more especially so in America. Wounds carefully protected from contact with impure air do not suppurate, and organic fluids do not putrefy. On the other hand, in a bad atmosphere sores become unhealthy, and are difficult to heal, erysipelas and hospital gangrene frequently set in, while the best prevention and the best means of cure for such afflictions is the greatest possible exposure to fresh air.

Vitiated air, as a consequence of over-crowding, aids the spread of measles, scarlet fever, and the much to be dreaded smallpox; it brings on ophthalmia, a troublesome inflammation of the eyes, and is not unfrequently the cause of the ricketty and scrofulous condition of children. Although exposure to cold does cause such affections as bronchitis, pneumonia, cold in the head, sore throat, and other affections of the respiratory organs, it is more frequently the case that they are the result of a sudden change of temperature, such as experienced in coming out of a crowded a.s.sembly in a close, badly-ventilated building, than by actually cold weather. This is decidedly and strikingly shown by the fact which Dr de Chaumont has quoted, that the British Army when in the Crimea, when lodged in tents during extremely rigorous weather, experienced a wonderful condition of health, such a thing as a cold being an unknown complaint; but when some of the men were placed in huts which were much warmer, and into which there was a smaller circulation of fresh air, the sick rate increased, and coughs and colds began to put in an appearance. Persons who during summer and winter sleep with their windows more or less open cannot endure a night spent in the chamber with the chimney closed and the window shut. A less refreshing sleep occupies the night, and a somewhat feverish sensation is felt next morning.

If in cold weather the window be opened only one inch at the top, the difference in the air in the bedroom is something quite beyond comprehension to those who have not paid attention to these things. See VENTILATION.

=Air, a.n.a.lysis of.= Priestley's discovery of oxygen gas in 1774 prepared the way for the knowledge of the real composition of air, which was discovered about the same time by Scheele and Lavoisier. Scheele's method of operating was by exposing some atmospheric air to a solution of sulphide of pota.s.sium. Lavoisier effected the same object by the combustion of iron wire and phosphorus, and subsequently by heating mercury on a flask filled with air for some time, just below its boiling point.

These, however, were but elementary methods, which, however creditable to the ingenuity of the great founders of modern chemistry, not only failed in accuracy, but took no account of the presence and amount of two most important const.i.tuents in the atmosphere, viz. carbonic anhydride (acid) and ammonia.

_Determination of Aqueous Vapour._ To effect this an aspirator must be used (see ASPIRATOR). This instrument is easily made, and is not expensive. The accompanying figure will ill.u.s.trate the arrangement generally adopted: _a_ is an aspirator made of galvanised iron or sheet zinc. It holds from 50 to 200 litres (from 11 to 44 gallons). By this means a known volume of air is drawn through the tubes marked _b_, _c_, _d_, _e_, which may be filled with pumice-stone moistened with strong sulphuric acid; but if the carbonic acid is to be estimated as well, _b_ and _c_ are filled with moist hydrate of lime (potash used to be employed, but hydrate of lime is to be preferred, as the potash absorbs oxygen), and _d_ and _e_ as above. Each of the tubes is accurately weighed previously to connecting them with the apparatus.

[Ill.u.s.tration]

It is imperative to have each of the tubes connected by perfectly air-tight joints. The gain of weight in _d_ and _e_ gives the water in _b_ and _c_ the carbonic acid.

_Determination of Carbonic Acid._ A better and perhaps more exact means of determining the carbonic acid is that invented by PETTENKOFER. It may be briefly described as follows:--Baryta water of definite strength is prepared and accurately standardised by a standard solution of oxalic acid. A portion of this baryta water is then made to act upon a definite quant.i.ty of air. It will absorb the whole of the carbonic acid in that air.

The alkalinity of the liquid will in consequence be diminished; it will take less of the oxalic-acid solution than before, which shows so much less caustic baryta, and from which the carbonic acid absorbed may be easily calculated.

_The actual a.n.a.lysis._ Two kinds of baryta water may be used, the one containing 7 grammes to the litre, the other three times that strength; 1 c. c. of the stronger = 3 m. grms. of carbonic acid; 1 c. c. of the weaker = 1 m. grm. The baryta water is best kept in the bottle represented below.

[Ill.u.s.tration]

The bottle (_a_) contains the baryta water. It has an accurately-fitting double-perforated stoppered caoutchouc. The left-hand tube is connected with the tube (_b_) containing pumice-stone moistened with potash, while the right-hand one is a syphon. When required for use the stop-c.o.c.k (_f_) is opened, and suction applied by a gla.s.s tube to F. The syphon is thus filled and the stop-c.o.c.k closed. If a pipette is required to be filled its nozzle is inserted at F, the stop-c.o.c.k compressed, and the fluid immediately rises into the pipette.

The air entering the bottle as the fluid decreases in _a_ is, of course, thoroughly deprived of its carbonic acid by the tubes at _b_.

The first thing to be done is to standardise the baryta solution by a solution of oxalic acid, containing 28636 grammes of crystallised oxalic acid to the litre.

Thirty c. c. of baryta solution are run into a small flask, and the oxalic acid run in from a Mohr's burette with float, the vanishing-point of the alkaline reaction being ascertained by delicate turmeric paper. As soon as a drop placed on turmeric paper does not give a brown ring the end is attained.

The actual a.n.a.lysis is performed by filling a bottle of known capacity, with the aid of a pair of bellows, with the air to be a.n.a.lysed, then distributing over its sides 45 c. c. of the baryta water it is left for half an hour. The turbid water is poured into a cylinder, closely secured, and allowed to deposit; then take out 30 c. c. by a pipette of the clear fluid, run in the solution of oxalic acid, multiply the volume used by 15, and deduct the produce from the c. c. of oxalic acid used for 45 c.

c. of the fresh baryta water. A different method has been suggested by Dr Angus Smith, viz. to measure the carbonic anhydride by the turbidities of the baryta water; this is, in fact, a colorimetric test. For rough approximative results Dr Smith's process will be found a very useful and convenient one. It depends upon the fact that the amount of carbonic acid in a given quant.i.ty of air will not produce a precipitate in a given quant.i.ty of lime or baryta water unless the carbonic acid is in excess.

The following is one of his tables:--Columns 1 and 2 give the rates of carbonic acid in the quant.i.ty of air which will produce no precipitate in half an ounce of lime water. Column 3 is the same as column 2; but 1416 c. c. (half an ounce) is added to give the corresponding size of the bottle, and column 4 gives the size of the bottle in ounces.

To be used when the point of observation is "no precipitate." Half an ounce of baryta water contains about 08 gramme of baryta.

Air at 0 C. and 760 millims. Bar.