【英语时差8,16】老式冰激凌的制作

Have you ever seen an old-fashioned ice cream maker¹? Nestled inside a wooden bucket, there's a metal canister with a hand crank on top. Cranking the handle scrapes the sweet, creamy mixture from the sides of the metal canister, which sits in a bath of ice water and salt. But what does salt have to do with freezing? Why not just use plain ice water?  A bath of salty ice water freezes ice cream faster than plain ice water could. And speedy freezing does more than cut down on cranking time on a hot summer's day. A fast freezing process also yields small crystals, insuring a silky texture². Slower freezing could make big crystals with an unpleasant crunch³, kind of like ice cream that's gritty with freezer-burn. Here's how salty ice water yields smooth ice cream faster than plain ice water could.

The coldest that plain ice water can get is 32 degrees Fahrenheit⁴, where there's a balance between the rates of melting and freezing. Add salt to the mix, though, and that energy balance tips, allowing the temperature to drop below 32 without freezing. Let's say you toss a handful of salt into ice water, and the temperature drops to 20 degrees. At this lower temperature, salty ice water can absorb more heat from the mixture inside the canister, and freeze it faster, than plain ice water could. And that means you can quit cranking sooner, and kick back on the porch to enjoy your silky-textured, old-fashioned ice cream.  

1 maker   

n.制造者，制造商

参考例句：

• He is a trouble maker，You must be distant with him.他是个捣蛋鬼，你不要跟他在一起。
• A cabinet maker must be a master craftsman.家具木工必须是技艺高超的手艺人。

2 texture   

n.(织物)质地；(材料)构造；结构；肌理

参考例句：

• We could feel the smooth texture of silk.我们能感觉出丝绸的光滑质地。
• Her skin has a fine texture.她的皮肤细腻。

3 crunch   

n.关键时刻；艰难局面；v.发出碎裂声

参考例句：

• If it comes to the crunch they'll support us.关键时刻他们是会支持我们的。
• People who crunch nuts at the movies can be very annoying.看电影时嘎吱作声地嚼干果的人会使人十分讨厌。

4 Fahrenheit   

n./adj.华氏温度；华氏温度计(的)

参考例句：

• He was asked for the boiling point of water in Fahrenheit.他被问到水的沸点是华氏多少度。
• The thermometer reads 80 degrees Fahrenheit.寒暑表指出华氏80度。