1852.] 



GAS PATENTS. 



11 



been shown by tlie same experiments that a tliermometer radiates 

 its lieat into space at the rate of one-tenth of a degree for every 

 tenth of unclouded skj' visible from the bulb. Other experiments 

 have established the law that the cooling of bodies by radiation 

 at night, is always in the same proportion to the clearness of the 

 sky, whatever be the actual temperature. Hence a thermome- 

 ter should be so placed that no portion of the sky shall be visible 

 from the bulb : that it must be screened from rain is self-evident, 

 and the same arrangement will fulfil both purposes, but it is not 

 necessary for the former of them that the covering should be of 

 a substantial nature, the very thinnest substance that can be in- 

 terposed being sufficient to arrest entirely the radiation of heat 

 into space. 



Such, then, being the principles upon which the place of a 

 therm6meter should be determined, it will be acknowledged that 

 a great proportion of those consulted for private information, 

 whatever else they may indicate, do not indicate the true tem- 

 perature of the air, in the sense understood by Meteorologists : and 

 hence a largo proportion of the discrepancies and anomalies 

 which make the collation of auv collection of observations so 

 discouraging a task. For example, in some observations made 

 at Quebec— 1828-1836 — {Trans. Hist. Soc, Vol. Ill,) we 

 find a sudden fall of two and a half degrees in the mean annual 

 temperature for the latter half of the series. 



Mean Temper. 9 A. M. Mean Temper. 9 A. M. 



— — 1832. 35.87 



1828 37.90 1833 35.85 



1829 37.81 1834 35.98 



1830 38 24 1835 •_._. 35,06 



1831 38.43 1836 34.83 



Mean 38.09 Mean 35.52 



This must have been caused by some change of the Instrument, 



or of its exposure, but no explanation is given of the circumstan- 

 ces. In a similar manner the mean temperature at Ancaster, 

 C.W., rose three or four degrees in 1 839, according to the observa- 

 tions of Dr. Craigie, published in HalTs Medical Journal, 1846, 

 and which are, in other respects, deserving of every confidence. 



Mean Temper. 9 A. M. Mean Temper. 9 A. M. 



— — 1839 47.59 



— — 1840 47.94 



— — 1841 47.66 



1835 44.09 1842 47.22 



1836 43.41 1843 45.80 



1837 43.45 1844 48.18 



1838 44.75 1845 j 48.33 



Mean . 



.44.17 



Mean. 



.47.53 



The difference in this case is equivalent to a change in geogra- 

 phical position of about 150 miles, or to a removal from Ancaster 

 to Ohio. Errors of position generally affect the final result 

 with their fall weight— -errors of graduation sometimes balance 

 one another upon the whole ; it is, therefore, of great import- 

 ance that the former be reduced, by attention to all the cir- 

 cumstances indicated. Practically, a box with lattice sides, not 

 too contracted, excluding rain and sun, but allowing free circula- 

 tion of air, while it checks the force of the wind, will generally 

 answer, but the observer must exercise his own judgment as to 

 whether heat is reflected iato this box from the wall or window 

 it faces, and place it so as to render that effect, which is appreci- 

 able from a considerable distance, almost impossible. 



The following table contains the horary corrections to obser- 

 vations of the thermometer in Canada, or the corrections neces- 

 sary to reduce the mean temperature, derived from observations 

 at certain incomplete hours of the day, to true means. They are 

 derived from the seven years of hourly observations at Toronto : 



5 A. M. 6 A. M 7 A. M. 8 A. M. 9 A. M. 10 A.M 11 A.M. JN 



1 P. M. y P. M. 3 P. M. 4 P. M. 8 P. M. 9 P. M. lUp. M. U P.M. Midn, 



January 



February ... 



March' 



April 



May .... 



June 



July ■ 



August 



Suptember . 



Octnber 



November . 

 December.. 



+2.46 

 -f3.ii2 

 + 1.35 

 .7.5 

 +7 83 

 +7.g8 

 +9 02 

 -t-7.89 

 -f6 77 

 -i-i.77 

 ■ 2.7(> 

 -)-2.07 



+I.«3 



+4.23 

 +4.75 



* 



5.40 

 1+5.21 

 +5 92 

 +6 57 

 +6.17 

 +4.71 

 +2.-52 

 l-f2.39 



+1.94 

 +4.34 

 +3.93 

 +3.22 

 +2.43 

 +2.41 

 +3,38 

 +3.28 

 +3.68 

 -i-3.94 

 -f-2-52 

 4:2,55 



+ .66|+),63 

 +3.29 +1.02 



+ 1.89 

 +1.09 

 +0.06 

 +0.10 

 —0,31 

 + 1.21 



+ m 



+1 66 

 -f 1,53 

 -f-2,l2 



—0.25 

 —1,01 

 —211 

 —1,82 

 —2,39 

 —2,26 

 —1,52 

 —1.0 1 

 +0 01 

 -F0,92 



—0.59 



0.95 



— 1.91 



-2.45 



-3.81 

 -3.49 

 -3.98 

 -4. 1 8 

 -3.47 

 -2.'I3 

 -1.41 

 -(1.53 



-1.70 

 -2.44 

 -3.14 

 -3.85 

 -4.92 

 -4.77 

 -5.49 

 -5 57 

 -4.85 

 -1.33 

 -2.44 

 -1.72 



-2.48 

 -3.56 

 -415 

 -4.86 

 -5.87 

 -5 88 

 -6.72 

 -6.39 

 -5.95 

 -5 36 

 -3.34 

 -2.52 



-2.92 

 -4 49 

 -479 

 -5 72 

 -6.83 

 -6 59 

 -7.58 

 -7.11 

 -6.58 

 -5.76 

 -3.74 

 -3.06 



-3.20 



-4.88 

 -5.31 

 -6.14 

 -7.13 

 -7.03 

 -8 26 

 -7.62 

 -6.96 

 -6.04 

 -3,82 



—3.16 



—4.90 

 —5.15 

 —6.16 

 —7.20 

 —7.37 

 —8.34 

 —7.98 

 —7.01 

 —5.85 

 —3 64 



—3.31 —3.13 



—2.63 —0.12 +0. 

 —4.47 —0.13 +0. 

 — 4.fi5-|-;i.03+j, 

 —5.81 +0.66 +1, 

 -7.17 4-0.43 +2 

 -7.60 -1-0.33 +2. 

 —8.25 -1-0.68 +2, 

 —7.79 -1-1,23 +2 

 —6.75 4-0,81 4-1, 

 —5.17 +0,48 -t-1. 

 —2.83 -j-n.' 9 -j-"^. 

 —2.47—0.12 4-a, 



07+0.44 +0 

 52 -1-106 -1-1. 

 ,00 +1.63 +2 

 ,78 +2.59+3 

 ,3! +3.29+4 

 ,44 -f3,80 +4 

 99 +4 24+5. 

 ,70+3.73 4-1 

 ,90;-|-2,94 4-3, 

 ,251-1-1,97 4-2 

 ,44+0.78! 4-1, 

 ,l8 4-'-),47'4-3. 



.77 +1-47 

 ,60 +1.73 

 ,01 +2.63 

 ,07 -1-3.22 

 ,20 -F5.02 

 ,76 4-5.15 

 ,21 +6.37 

 54 4-5.33 

 61 4-3.96 

 ,68 4-3.32 

 ,13 4-1.80 

 59 4-0.90 



It will be seen that, at 8 A. M. in the summer, and at 8 P. M. 

 in the winter, the eoi'rection is extremely small. Observations 

 made regularly at those two hours throughout the year, if a 

 greater number are not convenient, will therefore furnish very 

 accurate means, and they are, perhaps, the most convenient houi-s 

 in the twenty-four. Any three equidistant observations furnish 



Gas Patents, by Henry Croft, D. C. L, Professor of Chemistry 

 in the I'niveisity of Toronto. — (^Conlinued.) 



The principal object intended to be efteeted by the various 

 contrivances already mentioned, as applied to the purification of 

 gas, is the separation of the two gases carbonic acid and sul- 

 ],)huretted hydrogen ; the former, not being combustible, does not 

 in any way contribute to, but rather diminishes the brilliancy of 

 the gas, while the latter is objectionable, inasmuch as the light 

 which it gives out during burning is very feeble, a suftbcating 

 compound (sulphurous acid) is foi'med during the combustion, 

 and moreover, it possesses a disagreeable smell and poisonous 

 properties. In the older plans the ammonia was not separated, 



, true mean, such as 6 A. M., 2 P. M. 

 1 P. M., 11 P. M.; of these, the first 



and 10 P. M, 

 is now 2'ener 



or 7 A. M., 

 ally adopted. 



Note.— At p. 30, second column, line 25, for 29 992 read 29 922, p. 31, 

 in reference to the freezing mixture of 1 part salt, 2 parts snow, producing 

 a teniperalure of — 4 ° , or as some aulhorities give it — 5° , it should have 

 been added, that equal weights of sr.ow and sail reduce to 0*0, or' zero : both 

 mixtures should be tried if possible. 



only lime purifiers being used, but it was absorbed by the water 

 in the gasometer; its economic value is now so great, that as 

 before desci'ibed, it is separated by a special apparatus. 



Besides these substances which are thus removed from the 

 gaseous mixture, there are several other bodies which are deposi- 

 ted either in the hydraulic main, in the cooler,?, or in the purifiers, 

 and which of themselves possess very great illuminating jjower, 

 from containing a large proportion of carbon. These bodies will 

 burn with a brighter flame than even pure olefiant gas, and it 

 would therefore appear that the processes of coohng and purifying 

 have had the effect of diminishing the excellence of the e-as 



