Kaltura Share to Google Classroom Blackwell speaks about a method of keeping milk cool in the abscence of refrigeration. Grades: 3 4 5 6 7 8 9 10 11 12 Subjects: Social StudiesS.C. HistorySouth Carolina CultureAgriculture Collection: South Carolina CountiesMcCormick Series: Digital TraditionsAgricultureRichard Blackwell