Saliva is a watery substance formed in the mouths of animals, secreted by the salivary glands. Human saliva comprises 99.5% water, plus electrolytes, mucus, white blood cells, epithelial cells (which can be used to extract DNA), glycoproteins, enzymes (such as amylase and lipase), antimicrobial agents such as secretory IgA and lysozyme.
Take it on the arches does not mean simply Leave. It means Walk away. If Travis continues to break the chops of his dispatcher, he will not be driving a cab tonight. He will be walking home. I had no idea it was such an obscure term. It is dated, to be sure.
The central feature of an arch is the keystone, or the wedge-shaped stone at the very top of the arch. It is the last stone placed during construction, and it locks all the other stones of the arch into position. The keystone bears almost no weight, but is the center of redirecting the weight of the structure down and outwards. The Romans used arches with circular tops, called rounded arches, which were made of stone.