Tap water is generally cool enough, unless stored in heated cisterns.
Stain briefly with Ehrlich's hæmatoxylin (until nuclei are faint blue after washing with tap water).
Pouring some tap water into the cup, and filling it about one third full, he began to stir it round and round with a thermometer.
Tap water will do, but I would suggest distilled water for making the sensitizing solution of bichromate of potassium.
It is both possible and practical for a farmer to have his own tap water under pressure on the same plan as the city.