Chapter 5

However, it is to be noticed that there are two ways in which fire ceases to exist; it may go out either by exhaustion¹ or by extinction². That which is self-caused we call exhaustion, that due to its opposites extinction. [The former is that due to old age, the latter to violence.] But either of these ways in which fire ceases to be may be brought about by the same cause, for, when there is a deficiency of nutriment and the warmth can obtain no maintenance, the fire fails; and the reason is that the opposite, checking digestion³, prevents the fire from being fed. But in other cases the result is exhaustion,-when the heat accumulates excessively owing to lack of respiration⁴ and of refrigeration. For in this case what happens is that the heat, accumulating in great quantity, quickly uses up its nutriment and consumes it all before more is sent up by evaporation⁵. Hence not only is a smaller fire readily put out by a large one, but of itself the candle flame is consumed when inserted in a large blaze just as is the case with any other combustible⁶. The reason is that the nutriment in the flame is seized by the larger one before fresh fuel can be added, for fire is ever coming into being and rushing just like a river, but so speedily as to elude⁷ observation.

Clearly therefore, if the bodily heat must be conserved⁸ (as is necessary if life is to continue), there must be some way of cooling the heat resident in the source of warmth. Take as an illustration what occurs when coals are confined in a brazier. If they are kept covered up continuously by the so-called ‘choker’, they are quickly extinguished, but, if the lid is in rapid alternation lifted up and put on again they remain glowing for a long time. Banking⁹ up a fire also keeps it in, for the ashes, being porous¹⁰, do not prevent the passage of air, and again they enable it to resist extinction by the surrounding air by means of the supply of heat which it possesses. However, we have stated in The Problems the reasons why these operations, namely banking up and covering up a fire, have the opposite effects (in the one case the fire goes out, in the other it continues alive for a considerable time).

1 exhaustion   

n.耗尽枯竭，疲惫，筋疲力尽，竭尽，详尽无遗的论述

参考例句：

• She slept the sleep of exhaustion.她因疲劳而酣睡。
• His exhaustion was obvious when he fell asleep standing.他站着睡着了，显然是太累了。

2 extinction   

n.熄灭，消亡，消灭，灭绝，绝种

参考例句：

• The plant is now in danger of extinction.这种植物现在有绝种的危险。
• The island's way of life is doomed to extinction.这个岛上的生活方式注定要消失。

3 digestion   

n.消化，吸收

参考例句：

• This kind of tea acts as an aid to digestion.这种茶可助消化。
• This food is easy of digestion.这食物容易消化。

4 respiration   

n.呼吸作用；一次呼吸；植物光合作用

参考例句：

• They tried artificial respiration but it was of no avail.他们试做人工呼吸，可是无效。
• They made frequent checks on his respiration,pulse and blood.他们经常检查他的呼吸、脉搏和血液。

5 evaporation   

n.蒸发，消失

参考例句：

• Be careful not to lose too much liquid by evaporation.小心不要因蒸发失去太多水分。
• Our bodies can sweat,thereby losing heat by evaporation.我们的身体能出汗，由此可以蒸发散热。

6 combustible   

a. 易燃的,可燃的; n. 易燃物,可燃物

参考例句：

• Don't smoke near combustible materials. 别在易燃的材料附近吸烟。
• We mustn't take combustible goods aboard. 我们不可带易燃品上车。

7 elude   

v.躲避，困惑

参考例句：

• If you chase it,it will elude you.如果你追逐着它， 它会躲避你。
• I had dared and baffled his fury.I must elude his sorrow.我曾经面对过他的愤怒，并且把它挫败了；现在我必须躲避他的悲哀。

8 conserved   

v.保护，保藏，保存( conserve的过去式和过去分词 )

参考例句：

• He conserved his energy for the game. 他为比赛而养精蓄锐。 来自《简明英汉词典》
• Under these conditions, the total mechanical energy remains constant, or is conserved. 在这种条件下，总机械能保持不变或机械能保存。 来自辞典例句

9 banking   

n.银行业，银行学，金融业

参考例句：

• John is launching his son on a career in banking.约翰打算让儿子在银行界谋一个新职位。
• He possesses an extensive knowledge of banking.他具有广博的银行业务知识。

10 porous   

adj.可渗透的，多孔的

参考例句：

• He added sand to the soil to make it more porous.他往土里掺沙子以提高渗水性能。
• The shell has to be slightly porous to enable oxygen to pass in.外壳不得不有些细小的孔以便能使氧气通过。