QUESTIONS FOKMING A COAIPLKTE INDEX. 



XVH 



LESSON XLI. 

 Hydrogen-gas, what proportion is 



dangerous if inhaled ... ... 67 



Hydrogen-gas, what proportion 



may be recognised by its smell 68 

 Hydrogen-cas, may the use of it 



be considered dangerous ... 70 



Hydrogen-gas, what sources of it 



are there in our dwellings ... 69 

 Hydrogen, why will it burst into 



flame when coals become heated 100 

 Hydrogen, why does bi-carburet- 



ted burn with a whiter flume than 



common coal-gas 281 



Ice, why are blocks of it wrapped 



in flannel in summer time ... 154 

 Ice, why does it melt ... ... 325 



Icn, why does it occupy more space 



than water 752 



Ignis fatuus, what is it 318 



Incidence, what is the line of ... 519 

 Incidence, what is the angle of ... 521 

 India-rubber, where is it obtained 1254 

 Infants, why have they no teeth ... 1070 

 Insects, why have they a large 



number of eyes 1083 



Insects, why have they long pro- 

 jections from their heads ... 1100 

 Insects, why do they attach their 



eggs to leaves 1295 



Insect', why do they multiply so 

 numerously 1300 



LESSON XL1I. 



Insects, what is a larva 1302 



Insects, what is a pupa ... ... 1303 



Insects, what is a chrysalis ... 1304 



Insects, what u a nymph 1305 



Insects, why do they abound in 

 decaying substances and in pu- 

 trid waters 1313 



Insects, why do we see them in 



tanks of ruin-water 1314 



Iron articles, why are they intense- 

 ly cold in winter 132 



Iron articles, why do they usually 



feel cool, even when near a fire 132 

 Ironing-box, why does the iron 

 sometimes become too large for 



the box to receive it 335 



Ironing-box, why does the iron en- 

 ter ir, when partially cooled ... 336 

 Iron, why does it rust when wetted 768 



Jew'a-harps, why do they give mu- 

 sical sounds 851 



Jew's-harps, why will they not 

 produce loud sounds unless they 

 are applied to the mouih 852 



Jew's-harps, why does the altera- 

 tion of the form of the mouth al- 

 ter the sounds 853 



Kangaroos and opossums, why 

 hnve they pouches in which they 

 carry their young ... 1139 



LESSON XI.III. 

 Kettle-holdurs, of what use are 



they ............... 128 



Kettles and saucepans, why should 



the lids and fronts of, be kept 



bright ............ 206 



Kettles, why do they become en- 



crusted with stony deposites ... 7(12 

 Kite, why does it rise in the air ... 840 

 Kite-string, why does it feel hot 



when running through the hand 841 

 Kite, why does running with it 



cause it to ascend ......... 8 12 



Knowledge, why should we seek it 1 

 Knowledge, why does the posses- 



sion of it give us power ...... 2 



Knowledge, what are the benefits 



of .. ............ 3 



Latent heat, will the abstraction of 



it reduce the bulk of bodies ... 337 

 Latent heat, how do we know that 



it exists in air ......... 339 



Laugh, why do we ......... 1026 



Ligaments, what are they ...... 937 



Ligaments, why are they wrapped 



around the joints ......... 938 



Light, what is it ......... 451 



Leaves, why are they green ... 1181 

 Leaves, why do some turn yellow 1186 

 Leaves, why do they fall off in the 



autumn ............ 1187 



Leaves, how to make skeleton ... 1159 



LESSON XLIV 

 Leaves, why do they turn brown 



in autumn ............ 1183 



Lees crossed, why do we see the 



elevated leg move at regular in- 



tervals :. .......... 918 



Light, fit what velocity does it travel 453 

 Light, how long dues it take to 



travel from the sun to the earth 454 



Light, what nre the minor sources of 45? 



Light, what is a nty of ...... 458 



Light, what is a medium of ... 459 



Light, what is a beam of ...... 460 



Light, what is a pencil of ...... 461 



Light, what is the radiant point ... 4fi'2 



Light, what is the focus of ... 46.J 



Light, what is the constitution of a 



ray of ............... 464 



Light, why are its rnys white ... 4(io 

 Light, what are the estimated vib 



of 



465 

 470 



Light, what is the refraction of ... 



Light, is it refracted when it falls 

 upon a surface in a straight line 473 



Light, is the direction in wliich iis 

 rays are best dependent on the 

 d.-niities of the media ...... 474 



Light, why does a epoon look bent 

 when placed in a basin of water 477 



Light, wliy do we see the rays of 

 the sun burst through the clouds 

 in different directions .. 474* 



