This series introduces the core areas of chemical science, covering important concepts in an easy, accessible style. Each title contains a number of experiments and demonstrations, approached through the process of problem, hypothesis, experiment and conclusion. All the books support the QCA schemes of work and contain: definitions of important terms and explanations of key concepts; formulae and word equations; and the periodic table with explanatory notes. This title explores the concepts of the states of matter.

Almost twenty-five years after publishing Planning and Organizing the Postwar Air Force, 1943–1947, and a decade after publishing his definitive work, The Struggle for Air Force Independence, 1943–1947, Herman S. Wolk, retired Air Force senior historian, returns to the subject that capped his nearly fifty-year career with the Air Force history program. As Wolk explains, this briefwork is a reflective analysis.The United States Army's air arm waged a frustrating and uncertain battle during the interwar years to gain greater autonomy from the War Department. For the air arm, the key transition was the establishment in 1935 of the General Headquarters (GHQ) Air Force under Brig. Gen. Frank M. Andrews. The GHQ Air Force was the first American air force that consolidated all striking forces.For several years before the Japanese attack on Pearl Harbor, which triggered U.S. entry into World War II, President Franklin D. Roosevelt foresaw the major role that air power would play in the conflict, and he called for a massive buildup. The president wanted the major share of aircraft produced to go to the Allies. Consequently, he was sometimes at cross purposes with his Air Corps chief, Maj. Gen. Henry H. “Hap” Arnold, who was hard at work trying toincrease the Army's air capability. The formation in June 1944 of the Twentieth Air Force was a landmark event in the Army air arm's drive for independence. With B–29s to send against the Japanese home islands, the Twentieth gave the Army Air Forces (AAF) what Arnold termed “a Global Air Force.” Its formation set the precedent for that of the postwar Strategic Air Command, which provided the United States with its nuclear deterrence force in the Cold War.The lessons of World War II were many. Many also were the significant contributions of the AAF—tactical, strategic, support, humanitarian—that convinced President Harry S. Truman, Congress, and the American people that the creation of the United States Air Force (USAF) was necessary in the postwar era. Wolk makes the pivotal connections between politics and the searing experience of war to explain how and why the USAF was established. His analysis addresses not only technology, bureaucracy, and politics, but also people. The service's founding airmen were more than flyers and technologists; they were,above all, men of faith who believed in what they were doing. For many years they fought against long odds. The nation owes them a great debt.

Except in a few instances, since World War II no American soldier or sailor has been attacked by enemy air power. Conversely, no enemy soldier orsailor has acted in combat without being attacked or at least threatened by American air power. Aviators have brought the air weapon to bear against enemies while denying them the same prerogative. This is the legacy of the U.S. AirForce, purchased at great cost in both human and material resources.More often than not, aerial pioneers had to fight technological ignorance, bureaucratic opposition, public apathy, and disagreement over purpose.Every step in the evolution of air power led into new and untrodden territory, driven by humanitarian impulses; by the search for higher, faster, and farther flight; or by the conviction that the air way was the best way. Warriors have always coveted the high ground. If technology permitted them to reach it, men, women andan air force held and exploited it-from Thomas Selfridge, first among so many who gave that "last full measure of devotion"; to Women's Airforce Service Pilot Ann Baumgartner, who broke social barriers to become the first Americanwoman to pilot a jet; to Benjamin Davis, who broke racial barriers to become the first African American to command a flying group; to Chuck Yeager, a one-time non-commissioned flight officer who was the first to exceed the speed of sound; to John Levitow, who earned the Medal of Honor by throwing himself over a live flare to save his gunship crew; to John Warden, who began a revolution in air power thought and strategy that was put to spectacular use in the Gulf War.Industrialization has brought total war and air power has brought the means to overfly an enemy's defenses and attack its sources of power directly. Americans have perceived air power from the start as a more efficient means of waging war and as a symbol of the nation's commitment to technology to master challenges, minimize casualties, and defeat adversaries.

In the pantheon of air power spokesmen, Giulio Douhet holds center stage. His writings, more often cited than perhaps actually read, appear as excerpts and aphorisms in the writings of numerous other air power spokesmen, advocates-and critics. Though a highly controversial figure, the very controversy that surrounds him offers to us a testimonial of the value and depth of his work, and the need for airmen today to become familiar with his thought. The progressive development of air power to the point where, today, it is more correct to refer to aerospace power has not outdated the notions of Douhet in the slightest In fact, in many ways, the kinds of technological capabilities that we enjoy as a global air power provider attest to the breadth of his vision. Douhet, together with Hugh “Boom” Trenchard of Great Britain and William “Billy” Mitchell of the United States, is justly recognized as one of the three great spokesmen of the early air power era. This reprint is offered in the spirit of continuing the dialogue that Douhet himself so perceptively began with the first edition of this book, published in 1921. Readers may well find much that they disagree with in this book, but also much that is of enduring value. The vital necessity of Douhet’s central vision-that command of the air is all important in modern warfare-has been proven throughout the history of wars in this century, from the fighting over the Somme to the air war over Kuwait and Iraq.